Import statements sorted with isort and fixed MockBuilder.py (#266)

* Fixed missing closing bracket in the MockBuilder.py

* Import statements sorted with isort

BuildPlatform: assume python3 is available on Unix build host

BuildPlatform: assume git is available on Unix build host

waitForPackageSelfLink: wait a bit before reading the link

this helps for #207

BuildPlatform: assume 'which' command is available on Unix build host (#222)

python3: Finish python3 change. python2 breaking

* Based on mmlr's 2017 work to use Python3 with
changes and adjustments for the current codebase

python3: begin python3 fixes. print -> print()

nonChrootInit: Be more verbose about what's happening

Rename --list-build-dependencies option to --list-dependencies.

Print out test dependencies when combined with --test, otherwise print
build dependencies as before.

Cleanup: Remove unused imports.

Cleanup: Make some constructs more idiomatic.

* Change 'not x in y' to 'x not in y'.
* Use 'is' to compare None singleton.
* Use 'instanceof(x, y)' instead of 'type(x) == y'.
* Replace map builtin with list comprehension.
* Rename self argument to cls for static method.

Cleanup: Whitespace and line length cleanup.

BuildPlatformUnix: Add B_SYSTEM_PACKAGES_DIRECTORY override.

This allows --analyze-dependencies to work also on this platform when
given a --system-packages-directory.

Shallow init is also enough for --analyze-dependencies.

Implement local builders.

* provide info(), warn() to be used instead of print. By default outputs to stdout.
For builders, outputs to files.
* replace most calls to check_call by check_output, and log with info(). Also outputs
the outputs an eventual CalledProcessError output attribute.
* add option --local-builders to be used with --build-master: indicates how many
local builders to use instead of remote builders. If paramiko isn't available,
defaults to 1, otherwise 0.
* rename Builder to RemoteBuilder.
* remove changes of current directory: this doesn't work in a
multithreaded environnement. Policy.py is the most affected as it
expected to run in the packaging directory.

Use Unicode strings for warn() & sysExit().

haikuporter: Improve package command location detection

* Introduce which utility function to look for binaries
in your PATH
* Look in path first for default binary name if package
command not provided.

Add option to specify a system packages dir for build master.

It allows to set a system packages directory for the
BuildPlatformBuildMaster.

BuildPlatform: HaikuPorter most definitely wants bash.

Running HaikuPorter with ZSH for cmd:sh instead of Bash produces some rather odd and confusing errors, so don't do that.

Add BuildMaster mode and class.

Instead of building itself it distributes builds to builders via SSH
and coordinates pushing the dependencies around as needed.

Add option --no-system-packages to constrain used packages.

If supplied the system packages directory will not be added to the
list of package repositories used to resolve dependencies.

This means that only local packages from the packages path will be used
for the search of all dependency packages, including the search for the
main Haiku package itself. It therefore requires one to provide all
needed packages as part of the local packages but allows for more
control over what exact packages are visible.

BuildPlatform: Use findDirectory instead of hardcoding path.

Remove local check_output, we're now using Python 2.7.

Drop support for $haikuVersion.

* Referring the current haiku version explicitly is not needed, since
the RequiresUpdater takes care of setting the version of Haiku used
for building a package.

Fix #40: add explicit check for Haiku with package management.

Cleanup imports.

Activate new dependency resolution algorithm.

* Replace most occurrences of .PackageInfo with .DependencyInfo (except
of course where they are required for .hpkg creation).
* Switch Repository from .DependencyInfo files to .PackageInfo.
* Adjust BuildPlatform to delegate dependency resolution to
DependencyResolver (for both platforms, BuildPlatformHaiku is only
adding /system/packages as additional fallback repository)
* Adjust Port to use new dependency resolution.

Refactoring: Drop unused variables.

Refactoring: fix use of reserved keywords.

* Apparently, we were using reserved keywords as variable names, which
didn't seem to cause any problems, but could have done so in future
versions of Python.

Refactoring: use properties where it seems fit.

* Trying to be somewhat more Pythonic.

Revert to tab spacing for Pe's sake.

Try again with whitespace.

Second attempt to fix whitespace. Options are different on OS X.

Convert tabs to spaces.

Add cmd:awk and cmd:xargs requires for cross-builds.

Fix missing cmd:xres in PROVIDES for cross-compiles

This should fix #35 (ARM bootstrap).

Automatic whitespace cleanup - no functional change intended.

On Unix, make sure TARGET_ARCHITECTURE is set.

Only require LICENSES_DIRECTORY when it is needed.

* The only informational command that needs it is --lint.

Allow informational commands (e.g. --lint) to run on Linux.

* Introduce support for shallow initialization to Main and
BuildPlatform classes and make use of that for the informational
commands.

Add some missing target-arch provides for haiku.

* this gets the source collection step of the bootstrap build to the
part where it actually starts building source packages

BuildPlatformHaiku: Find canonically named Haiku system package

/boot/common has been removed

Mostly the changes are straight-forward (don't look in /boot/common,
adjust paths). A notable change concerns the resolution of port
dependencies: We no longer simply include all /boot/system packages in
the chroot, but only those that have to be pulled in according to the
dependency resolution. This may break some recipes that don't declare
all the things they actually require for building, but have worked
previously due to those dependencies living in /boot/system.

Fix and robustify waiting for build package (de-)activation

* in case of an existing symlink, check its target for both activation
and deactivation (we missed the latter case last time)
* negate the check and look for the packaging folder as symlink target
instead of checking for '..' (system) and 'common' - a package with
the same name could be installed in '/boot/home', for example.

Wait for activation/deactivation of build packages.

* the package daemon is activating/deactivating with a bit of delay,
so we need to wait for the updated symlink in the package-links
folder

Consider buildhost packages when building on Haiku.

* additionally, refactor resolving of dependencies to hopefully
be a bit clearer

Drop superfluous invocation of getHaikuVersion().

Add cmd:awk as build-target provides for cross-build.

Change machine triple for x86_gcc2 to i586-pc-haiku

The old one was more correct in principle, but we'd have to apply that
change in the autotools as well and make sure that all build systems
using them still work. Too much work for little benefit.

BuildPlatformUnix: add more implicit provides

Remove work-around for resolved issue

BuildPlatformUnix: add more implicit target provides

Add some missing implicit target provides.

* coreutils, diffutils and cmd:sh are referenced from the haikuports
repository

BuildPlatformUnix: ensure secondary cross devel pkgs are given

Fix resolving of dependencies:

* resolving required and prerequired packages needs to pass the
packages folder before the work repository, as otherwise HaikuPorter
would try to rebuild ports that were already built before
* add support to BuildPlatform.resolveDependencies() for passing in
a list of fallback repositories, which will be searched after the
common/system repositories
* resolving prerequired packages needs to pass the work repository as
a fallback repository, such that it will only be considered if a
prerequired packages isn't provided by the system (in which case it
will be built by HaikuPorter)

Implement strict separation of buildhost and target packages.

* REQUIRES and BUILD_REQUIRES refer to target architecture packages,
while BUILD_PREREQUIRES refers to buildhost architecture packages
* added support for building prerequired packages when needed
* add a separate set of implicit target packages to BuildPlatformUnix,
which only contains the 'haiku' package

Keep secondary arch Haiku cross devel package's lib/ structure

* Symlink the cross devel package's lib dir, not its secondary arch
subdir, to the compiler's sysroot lib dir. Necessary since we now
build the cross compiler as a secondary compiler, so it searches the
subdir.
* Add temporary work-around: Currently gcc calls the lib subdir "gcc4"
while it should have the name of the secondary architecture. Create a
respective symlink.

BuildPlatformUnix: add secondary tool chain to implicit provides

BuildPlatformUnix: remove debug output

BuildPlatformUnix: simplify include/lib dir setup

ATM the include and lib directories we create for the cross tools are
there mostly for aesthetical reasons. ATM they are just symlinks to the
respective directories of the extracted Haiku sysroot package and are
used as the target of the symlinks we create in the actual cross tools
directory. So we can just as well use a simple directory layout.

Support building secondary arch packages from regular recipes

* Add settings SECONDARY_CROSS_DEVEL_PACKAGES, SECONDARY_CROSS_TOOLS,
and SECONDARY_TARGET_ARCHITECTURES to config file and command line
option --secondary-cross-devel-packages, overriding the first.
SECONDARY_TARGET_ARCHITECTURES is the list of secondary target
architectures that ports may be built for (for a hybrid target).
SECONDARY_CROSS_TOOLS is the respectively matching list of cross
tools directories and SECONDARY_CROSS_DEVEL_PACKAGES the list of
Haiku cross development sysroot packages.
* Repository: For all configured secondary architectures add derived
ports.
* BuildPlatformUnix:
- setupNonChrootBuildEnvironment()/cleanNonChrootBuildEnvironment() do
now support an optional secondaryArchitecture parameter which is set
when building a port for a secondary architecture. The build
environment is set up using the respective cross tools and Haiku
cross devel package.
- Fix setting up the system include and library search paths for
gcc 4. It has other paths built in.
* Recipes can now set a SECONDARY_ARCHITECTURES (similar to
ARCHITECTURES) to indicate for which secondary architectures the port
can be built.
* Add new shell variables effectiveTargetArchitecture,
effectiveTargetMachineTriple, and effectiveTargetMachineTripleAsName
which are set to the values for the target architecture we are
actually building for (i.e. the primary or secondary architecture).
When cross-compiling the pre-existing target* variables continue to
correspond to the primary architecture.
* The variables binDir, sbinDir, libDir, includeDir, oldIncludeDir,
developLibDir are set to a respective subdirectory when building for
a secondary architecture.

Add support for meta-ports, specifically 'meta_portsfile'

* a meta-port is a port that just builds other (non-meta) ports, but it
doesn't provide any sources or build actions of its own
* when building a list of ports specified via --portsfile, the meta-
port 'meta_portsfile' is now being used to group all the required
ports (pulling in any runtime requirements, too)
* when building only source packages, consider all packages stable, as
otherwise sources for not-yet-stable packages could not be collected
(one would have to mark them as stable manually)
* add more missing implicit build provides to Unix build platform

Add some missing implicit provides on Unix build platform.

Let BuildProfile default to configured target architecture.

* otherwise, it's impossible to build for a target architecture when
not using the cross-repository - this however is needed for building
the source packages required by a standard Haiku image

More work on building only source packages.

* building source packages for a list of ports is now basically
possible, but the current limits of dependency resolution have
the effect that not all required ports are being pulled in

Add support for separate output directory

* Add configuration file value OUTPUT_DIRECTORY specifying the directory
where haikuporter shall write files. It mirrors the ports repository
directory layout. The default value is the repository path.
* Add configuration file value DOWNLOAD_IN_PORT_DIRECTORY. Only
meaningful, if OUTPUT_DIRECTORY is specified. In that case a value of
"yes" will still cause the download directory to be placed in the port
directory. This may be useful when building for different target
architectures in separate output directories -- the downloads can thus
be shared.

Unifiy the Options and GlobalConfig somewhat

* Module GlobalConfig is replaced with new module Configuration. The
global variable globalConfiguration is gone. Instead Configuration
provides getter methods.
* For several of the (newer) command line options there are now optional
configuration file entries. If given the command line values override
the configuration file values. Configuration also provides getter
methods for these options, which should be used instead of
getOption().

BuildPlatformUnix: add more stuff to implicit build provides

Unix build: Fix package activation and cross package installation

* BuildPlatform*: add getCrossToolsBasePrefix(). It returns a base
installation prefix when building cross packages. Since those must
work on the build platform, we must make sure that the prefix they are
configured with is actually the location they can be installed. That
is mostly of interest on non-Haiku build platforms where we build
without a chroot. Consequently this prefix is outside the work
directory, a directory named "cross_tools" in the repository root.
* Extract all required packages in "system" rather than "common". This
simplifies things mostly for cross packages, since their headers and
libraries will then be automatically in the compiler search paths.
* Create the package symlinks directory and the .self symlink for all
required packages. Also mostly relevant for cross packages, since
those need to be able to resolve their built-in absolute paths.

BuildPlatform: extend getCrossToolsBinPath()

* Rename to getCrossToolsBinPaths() and return an array of paths.
* For BuildPlatformUnix we also include <workDir>/boot/common/bin so
the cross tools (other than binutils and gcc) are also in the path.

BuildPlatformUnix: install cross packages in <work>/boot/common

BuildPlatformUnix: improved dependency resolution for pre-reqs

Use the same algorithm for resolving pre-requires and requires, for the
former only consider cross packages, though.

BuildPlatformUnix: add more implicit build provides

Fix crossSysrootDir for non-Haiku build platforms

* BuildPlatform: Determine target architecture and cross sysroot dir.
Add respective getTargetArchitecture() and getCrossSysrootDirectory()
method.
* BuildPlatformUnix: Make getInstallDestDir() synonymous with
getCrossSysrootDirectory().
* Set the crossSysrootDir shell variable in
Port._updateShellVariables() instead of in Main. This way it gets
adjusted depending on whether we're in a chroot or not.

BuildPlatformUnix: add implicit build provides "cmd:cmake"

BuildPlatform: missing import

BuildPlatformUnix: some architecture/machine fine tuning

* The architecture we pass to our base class needs to be a packaging
architecture. Try to find a match. If unsuccessful use "any". It
shouldn't really matter -- we just need it to be valid so "package"
doesn't complain.
* Replace the first component of the machine triple we get from gcc with
the architecture we get from os.uname(). This works around the issue
that in a linux32 environment gcc still reports the x86_64 machine.
For FreeBSD we'll need to find a different solution. We'll probably
have to add 64-bit platform handling logic to the gcc_bootstrap
recipe instead.

BuildPlatformUnix: add more implicit build platform provides

BuildPlatformUnix.init(): fix copy-and-paste mess-up

Package.removeBuildPackage(): also delegate to buildPlatform

Fixes the issue that shutil.rmtree() doesn't work for non-directories
and is nicer anyway.

BuildPlatform: let subclass determine architecture

BuildPlatformHaiku already knows the architecture and the architecture
from the machine triple isn't necessarily also a valid package
architecture.

BuildPlatformHaiku: build fixes

Complete support for non-Haiku build platforms

* Port.build(): When not using chroot, let buildPlatform set up/clean up
a suitable environment. Currently not supported for
BuildPlatformHaiku. BuildPlatformUnix sets up a cross-sysroot subdir
in the work directory. It extracts the haiku_cross_devel_sysroot
package to the boot/system and the other required packages to the
boot/common subtree. Furthermore it sets up a cross-tools directory
with bin, sys-include, lib subdirs. The former points to the cross
tools bin dir and is added to PATH. The latter two refer to
boot/system/develop/{headers,lib} and are symlinked temporarily into
the cross tools directory, so the headers and libraries are picked up
correctly. Not so nice, but I haven't found a cleaner way to do that.
Wrapper scripts might work.
* Package.activateBuildPackage(): delegate to buildPlatform.
BuildPlatformHaiku uses the previous code. BuildPlatformUnix sets up
the package symlinks directory for the package in the cross
sysroot/packages directory (currently only the .self symlink).
* Define installDestDir shell variable when cross-building on non-Haiku.

Port: move dependency resolution to BuildPlatform*

* BuildPlatformHaiku uses pkgman to resolve the dependencies as done
before.
* BuildPlatformUnix doesn't need to actually resolve pre-requires.
It just checks them against a list that is expected to be available.
Requires are resolved using RequiresUpdater. That should be good
enough for the bootstrap packages.

BuildPlatformUnix: check mandatory options

Add --system-mimedb and --command-mimeset options

BuildPlatform*: move more initialization to init()

BuildPlatform: add getLicensesDirectory()

Only use chroot on Haiku

Start with a build platform abstraction

* Add '--cross-devel-package' option to specify the path to the cross
development package. Can be used for cross-compiling.
* Add module BuildPlatform which exports a buildPlatform variable, which
is initialized to an instance of BuildPlatformHaiku or
BuildPlatformUnix as appropriate.
* Move findDirectory() to BuildPlatformHaiku. BuildPlatformUnix has a
version with some hard-coded mappings.
* Add PackageInfo class. Very simple ATM. It only extracts the version
and the architecture from a package file.
* Rework Main._initGlobalShellVariables() somewhat: Extracting the Haiku
version from the build platform's system haiku package is obviously
not correct when cross-building. Also add support for non-Haiku build
platforms.
* Remove no longer needed MachineArchitecture.getBuildTripleFor().

Drop support for $haikuVersion.

* Referring the current haiku version explicitly is not needed, since
the RequiresUpdater takes care of setting the version of Haiku used
for building a package.

Fix #40: add explicit check for Haiku with package management.

Cleanup imports.

Activate new dependency resolution algorithm.

* Replace most occurrences of .PackageInfo with .DependencyInfo (except
of course where they are required for .hpkg creation).
* Switch Repository from .DependencyInfo files to .PackageInfo.
* Adjust BuildPlatform to delegate dependency resolution to
DependencyResolver (for both platforms, BuildPlatformHaiku is only
adding /system/packages as additional fallback repository)
* Adjust Port to use new dependency resolution.

Refactoring: Drop unused variables.

Refactoring: fix use of reserved keywords.

* Apparently, we were using reserved keywords as variable names, which
didn't seem to cause any problems, but could have done so in future
versions of Python.

Refactoring: use properties where it seems fit.

* Trying to be somewhat more Pythonic.

Revert to tab spacing for Pe's sake.

Try again with whitespace.

Second attempt to fix whitespace. Options are different on OS X.

Convert tabs to spaces.

Add cmd:awk and cmd:xargs requires for cross-builds.

Fix missing cmd:xres in PROVIDES for cross-compiles

This should fix #35 (ARM bootstrap).

Automatic whitespace cleanup - no functional change intended.

On Unix, make sure TARGET_ARCHITECTURE is set.

Only require LICENSES_DIRECTORY when it is needed.

* The only informational command that needs it is --lint.

Allow informational commands (e.g. --lint) to run on Linux.

* Introduce support for shallow initialization to Main and
BuildPlatform classes and make use of that for the informational
commands.

Add some missing target-arch provides for haiku.

* this gets the source collection step of the bootstrap build to the
part where it actually starts building source packages

BuildPlatformHaiku: Find canonically named Haiku system package

/boot/common has been removed

Mostly the changes are straight-forward (don't look in /boot/common,
adjust paths). A notable change concerns the resolution of port
dependencies: We no longer simply include all /boot/system packages in
the chroot, but only those that have to be pulled in according to the
dependency resolution. This may break some recipes that don't declare
all the things they actually require for building, but have worked
previously due to those dependencies living in /boot/system.

Fix and robustify waiting for build package (de-)activation

* in case of an existing symlink, check its target for both activation
and deactivation (we missed the latter case last time)
* negate the check and look for the packaging folder as symlink target
instead of checking for '..' (system) and 'common' - a package with
the same name could be installed in '/boot/home', for example.

Wait for activation/deactivation of build packages.

* the package daemon is activating/deactivating with a bit of delay,
so we need to wait for the updated symlink in the package-links
folder

Consider buildhost packages when building on Haiku.

* additionally, refactor resolving of dependencies to hopefully
be a bit clearer

Drop superfluous invocation of getHaikuVersion().

Add cmd:awk as build-target provides for cross-build.

Change machine triple for x86_gcc2 to i586-pc-haiku

The old one was more correct in principle, but we'd have to apply that
change in the autotools as well and make sure that all build systems
using them still work. Too much work for little benefit.

BuildPlatformUnix: add more implicit provides

Remove work-around for resolved issue

BuildPlatformUnix: add more implicit target provides

Add some missing implicit target provides.

* coreutils, diffutils and cmd:sh are referenced from the haikuports
repository

BuildPlatformUnix: ensure secondary cross devel pkgs are given

Fix resolving of dependencies:

* resolving required and prerequired packages needs to pass the
packages folder before the work repository, as otherwise HaikuPorter
would try to rebuild ports that were already built before
* add support to BuildPlatform.resolveDependencies() for passing in
a list of fallback repositories, which will be searched after the
common/system repositories
* resolving prerequired packages needs to pass the work repository as
a fallback repository, such that it will only be considered if a
prerequired packages isn't provided by the system (in which case it
will be built by HaikuPorter)

Implement strict separation of buildhost and target packages.

* REQUIRES and BUILD_REQUIRES refer to target architecture packages,
while BUILD_PREREQUIRES refers to buildhost architecture packages
* added support for building prerequired packages when needed
* add a separate set of implicit target packages to BuildPlatformUnix,
which only contains the 'haiku' package

Keep secondary arch Haiku cross devel package's lib/ structure

* Symlink the cross devel package's lib dir, not its secondary arch
subdir, to the compiler's sysroot lib dir. Necessary since we now
build the cross compiler as a secondary compiler, so it searches the
subdir.
* Add temporary work-around: Currently gcc calls the lib subdir "gcc4"
while it should have the name of the secondary architecture. Create a
respective symlink.

BuildPlatformUnix: add secondary tool chain to implicit provides

BuildPlatformUnix: remove debug output

BuildPlatformUnix: simplify include/lib dir setup

ATM the include and lib directories we create for the cross tools are
there mostly for aesthetical reasons. ATM they are just symlinks to the
respective directories of the extracted Haiku sysroot package and are
used as the target of the symlinks we create in the actual cross tools
directory. So we can just as well use a simple directory layout.

Support building secondary arch packages from regular recipes

* Add settings SECONDARY_CROSS_DEVEL_PACKAGES, SECONDARY_CROSS_TOOLS,
and SECONDARY_TARGET_ARCHITECTURES to config file and command line
option --secondary-cross-devel-packages, overriding the first.
SECONDARY_TARGET_ARCHITECTURES is the list of secondary target
architectures that ports may be built for (for a hybrid target).
SECONDARY_CROSS_TOOLS is the respectively matching list of cross
tools directories and SECONDARY_CROSS_DEVEL_PACKAGES the list of
Haiku cross development sysroot packages.
* Repository: For all configured secondary architectures add derived
ports.
* BuildPlatformUnix:
- setupNonChrootBuildEnvironment()/cleanNonChrootBuildEnvironment() do
now support an optional secondaryArchitecture parameter which is set
when building a port for a secondary architecture. The build
environment is set up using the respective cross tools and Haiku
cross devel package.
- Fix setting up the system include and library search paths for
gcc 4. It has other paths built in.
* Recipes can now set a SECONDARY_ARCHITECTURES (similar to
ARCHITECTURES) to indicate for which secondary architectures the port
can be built.
* Add new shell variables effectiveTargetArchitecture,
effectiveTargetMachineTriple, and effectiveTargetMachineTripleAsName
which are set to the values for the target architecture we are
actually building for (i.e. the primary or secondary architecture).
When cross-compiling the pre-existing target* variables continue to
correspond to the primary architecture.
* The variables binDir, sbinDir, libDir, includeDir, oldIncludeDir,
developLibDir are set to a respective subdirectory when building for
a secondary architecture.

Add support for meta-ports, specifically 'meta_portsfile'

* a meta-port is a port that just builds other (non-meta) ports, but it
doesn't provide any sources or build actions of its own
* when building a list of ports specified via --portsfile, the meta-
port 'meta_portsfile' is now being used to group all the required
ports (pulling in any runtime requirements, too)
* when building only source packages, consider all packages stable, as
otherwise sources for not-yet-stable packages could not be collected
(one would have to mark them as stable manually)
* add more missing implicit build provides to Unix build platform

Add some missing implicit provides on Unix build platform.

Let BuildProfile default to configured target architecture.

* otherwise, it's impossible to build for a target architecture when
not using the cross-repository - this however is needed for building
the source packages required by a standard Haiku image

More work on building only source packages.

* building source packages for a list of ports is now basically
possible, but the current limits of dependency resolution have
the effect that not all required ports are being pulled in

Add support for separate output directory

* Add configuration file value OUTPUT_DIRECTORY specifying the directory
where haikuporter shall write files. It mirrors the ports repository
directory layout. The default value is the repository path.
* Add configuration file value DOWNLOAD_IN_PORT_DIRECTORY. Only
meaningful, if OUTPUT_DIRECTORY is specified. In that case a value of
"yes" will still cause the download directory to be placed in the port
directory. This may be useful when building for different target
architectures in separate output directories -- the downloads can thus
be shared.

Unifiy the Options and GlobalConfig somewhat

* Module GlobalConfig is replaced with new module Configuration. The
global variable globalConfiguration is gone. Instead Configuration
provides getter methods.
* For several of the (newer) command line options there are now optional
configuration file entries. If given the command line values override
the configuration file values. Configuration also provides getter
methods for these options, which should be used instead of
getOption().

BuildPlatformUnix: add more stuff to implicit build provides

Unix build: Fix package activation and cross package installation

* BuildPlatform*: add getCrossToolsBasePrefix(). It returns a base
installation prefix when building cross packages. Since those must
work on the build platform, we must make sure that the prefix they are
configured with is actually the location they can be installed. That
is mostly of interest on non-Haiku build platforms where we build
without a chroot. Consequently this prefix is outside the work
directory, a directory named "cross_tools" in the repository root.
* Extract all required packages in "system" rather than "common". This
simplifies things mostly for cross packages, since their headers and
libraries will then be automatically in the compiler search paths.
* Create the package symlinks directory and the .self symlink for all
required packages. Also mostly relevant for cross packages, since
those need to be able to resolve their built-in absolute paths.

BuildPlatform: extend getCrossToolsBinPath()

* Rename to getCrossToolsBinPaths() and return an array of paths.
* For BuildPlatformUnix we also include <workDir>/boot/common/bin so
the cross tools (other than binutils and gcc) are also in the path.

BuildPlatformUnix: install cross packages in <work>/boot/common

BuildPlatformUnix: improved dependency resolution for pre-reqs

Use the same algorithm for resolving pre-requires and requires, for the
former only consider cross packages, though.

BuildPlatformUnix: add more implicit build provides

Fix crossSysrootDir for non-Haiku build platforms

* BuildPlatform: Determine target architecture and cross sysroot dir.
Add respective getTargetArchitecture() and getCrossSysrootDirectory()
method.
* BuildPlatformUnix: Make getInstallDestDir() synonymous with
getCrossSysrootDirectory().
* Set the crossSysrootDir shell variable in
Port._updateShellVariables() instead of in Main. This way it gets
adjusted depending on whether we're in a chroot or not.

BuildPlatformUnix: add implicit build provides "cmd:cmake"

BuildPlatform: missing import

BuildPlatformUnix: some architecture/machine fine tuning

* The architecture we pass to our base class needs to be a packaging
architecture. Try to find a match. If unsuccessful use "any". It
shouldn't really matter -- we just need it to be valid so "package"
doesn't complain.
* Replace the first component of the machine triple we get from gcc with
the architecture we get from os.uname(). This works around the issue
that in a linux32 environment gcc still reports the x86_64 machine.
For FreeBSD we'll need to find a different solution. We'll probably
have to add 64-bit platform handling logic to the gcc_bootstrap
recipe instead.

BuildPlatformUnix: add more implicit build platform provides

BuildPlatformUnix.init(): fix copy-and-paste mess-up

Package.removeBuildPackage(): also delegate to buildPlatform

Fixes the issue that shutil.rmtree() doesn't work for non-directories
and is nicer anyway.

BuildPlatform: let subclass determine architecture

BuildPlatformHaiku already knows the architecture and the architecture
from the machine triple isn't necessarily also a valid package
architecture.

BuildPlatformHaiku: build fixes

Complete support for non-Haiku build platforms

* Port.build(): When not using chroot, let buildPlatform set up/clean up
a suitable environment. Currently not supported for
BuildPlatformHaiku. BuildPlatformUnix sets up a cross-sysroot subdir
in the work directory. It extracts the haiku_cross_devel_sysroot
package to the boot/system and the other required packages to the
boot/common subtree. Furthermore it sets up a cross-tools directory
with bin, sys-include, lib subdirs. The former points to the cross
tools bin dir and is added to PATH. The latter two refer to
boot/system/develop/{headers,lib} and are symlinked temporarily into
the cross tools directory, so the headers and libraries are picked up
correctly. Not so nice, but I haven't found a cleaner way to do that.
Wrapper scripts might work.
* Package.activateBuildPackage(): delegate to buildPlatform.
BuildPlatformHaiku uses the previous code. BuildPlatformUnix sets up
the package symlinks directory for the package in the cross
sysroot/packages directory (currently only the .self symlink).
* Define installDestDir shell variable when cross-building on non-Haiku.

Port: move dependency resolution to BuildPlatform*

* BuildPlatformHaiku uses pkgman to resolve the dependencies as done
before.
* BuildPlatformUnix doesn't need to actually resolve pre-requires.
It just checks them against a list that is expected to be available.
Requires are resolved using RequiresUpdater. That should be good
enough for the bootstrap packages.

BuildPlatformUnix: check mandatory options

Add --system-mimedb and --command-mimeset options

BuildPlatform*: move more initialization to init()

BuildPlatform: add getLicensesDirectory()

Only use chroot on Haiku

Start with a build platform abstraction

* Add '--cross-devel-package' option to specify the path to the cross
development package. Can be used for cross-compiling.
* Add module BuildPlatform which exports a buildPlatform variable, which
is initialized to an instance of BuildPlatformHaiku or
BuildPlatformUnix as appropriate.
* Move findDirectory() to BuildPlatformHaiku. BuildPlatformUnix has a
version with some hard-coded mappings.
* Add PackageInfo class. Very simple ATM. It only extracts the version
and the architecture from a package file.
* Rework Main._initGlobalShellVariables() somewhat: Extracting the Haiku
version from the build platform's system haiku package is obviously
not correct when cross-building. Also add support for non-Haiku build
platforms.
* Remove no longer needed MachineArchitecture.getBuildTripleFor().