Add a features.h to auto enable _DEFAULT_SOURCE

Unless __STRICT_ANSI__ is defined (as it is when running the compiler in
--std=c89 or --std=c99, but not when running it without any specific
args), we can enable these by default and behave like most other
systems. I don't know why no one has done this yet despite suggesting it
multiple times and people prefer to #define _BSD_SOURCE manually
everywhere.

Remove all places in our Jamfiles and sources where it had been defined.
_DEFAULT_SOURCE is now enabled by default for all sources of Haiku, since we
let the compiler use GNU extensions (no strict C standard specified on
command line)

Use _DEFAULT_SOURCE as the define name to match current versions of
glibc. Enable it if _BSD_SOURCE is #defined in compiler flags, for
backward compatibility.

Change-Id: I6db04da5f6db437723cdfba3478f5094a69d7727
Reviewed-on: https://review.haiku-os.org/c/1633
Reviewed-by: Jérôme Duval <jerome.duval@gmail.com>

Protect all BSD extensions with _BSD_SOURCE

* Do not define the symbols by default, as they are not in the default
libraries.
* Adjust jamfiles of all code using BSD extensions to define
_BSD_SOURCE.
* This makes Haiku slightly more compliant to standard C/POSIX.

Add the ncurses headers dependency where needed.

Should fix the build for real.

Outsource ncurses.

Discard Termcap and switch console apps to use Terminfo

* Switch bash, debugger, less, telnet[d] and top apps to use termcap
functionality provided by ncurses lib instead of GNU libtermcap.so;
* NetBSD version of tput utility replaced with ncurses' one. Fixes #9606;
* terminfo database is provided as mandatory package installed during
building target system;
* Remove libtermcap module. The termcap database source and
corresponding build rules are not removed to provide backward compatibility -
until all optional packages will be rebuild on upcoming system version
using terminfo. Note that gcc2 builds may require to provide termcap a bit
longer in the sake of binary compatibility with R5 era apps.

* Moved termcap.h to headers/libs/termcap/, where it belongs.
* Removed the headers/gnu from the default headers (the Jamfiles needing it
use it explicitly, now) and moved it under headers/compatibility/.
* Added libgnu.so to the image. Still untested, though.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@32481 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Prefixed the variables NETWORK_LIBS, NETAPI_LIB, and
SELECT_UNAME_ETC_LIB with TARGET_ and introduced HAIKU_* and HOST_*
counterparts.
* Use HOST_NETWORK_LIBS for building remote_disk_server.
* Also got rid of {R5,BONE,DANO,HAIKU}_COMPATIBLE.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@21912 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Ported libtelnet.a and telnetd from FreeBSD.
* The subdirectory is called "libtelnet" instead of "telnet" (as usual), since telnetd
expects some headers to be found in libtelnet/ (which I could have changed as well,
just in case you very much prefer telnet/).
* I needed to disable some stuff to make it compile, and it's absolutely not tested,
so it might as well not work yet.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@19488 a95241bf-73f2-0310-859d-f6bbb57e9c96

Protect all BSD extensions with _BSD_SOURCE

* Do not define the symbols by default, as they are not in the default
libraries.
* Adjust jamfiles of all code using BSD extensions to define
_BSD_SOURCE.
* This makes Haiku slightly more compliant to standard C/POSIX.

Add the ncurses headers dependency where needed.

Should fix the build for real.

Outsource ncurses.

Discard Termcap and switch console apps to use Terminfo

* Switch bash, debugger, less, telnet[d] and top apps to use termcap
functionality provided by ncurses lib instead of GNU libtermcap.so;
* NetBSD version of tput utility replaced with ncurses' one. Fixes #9606;
* terminfo database is provided as mandatory package installed during
building target system;
* Remove libtermcap module. The termcap database source and
corresponding build rules are not removed to provide backward compatibility -
until all optional packages will be rebuild on upcoming system version
using terminfo. Note that gcc2 builds may require to provide termcap a bit
longer in the sake of binary compatibility with R5 era apps.

* Moved termcap.h to headers/libs/termcap/, where it belongs.
* Removed the headers/gnu from the default headers (the Jamfiles needing it
use it explicitly, now) and moved it under headers/compatibility/.
* Added libgnu.so to the image. Still untested, though.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@32481 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Prefixed the variables NETWORK_LIBS, NETAPI_LIB, and
SELECT_UNAME_ETC_LIB with TARGET_ and introduced HAIKU_* and HOST_*
counterparts.
* Use HOST_NETWORK_LIBS for building remote_disk_server.
* Also got rid of {R5,BONE,DANO,HAIKU}_COMPATIBLE.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@21912 a95241bf-73f2-0310-859d-f6bbb57e9c96

* Ported libtelnet.a and telnetd from FreeBSD.
* The subdirectory is called "libtelnet" instead of "telnet" (as usual), since telnetd
expects some headers to be found in libtelnet/ (which I could have changed as well,
just in case you very much prefer telnet/).
* I needed to disable some stuff to make it compile, and it's absolutely not tested,
so it might as well not work yet.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@19488 a95241bf-73f2-0310-859d-f6bbb57e9c96