Copy stable/10@r272459 to releng/10.1 as part of
the 10.1-RELEASE process.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Replace all known uses of ln in the build process with appropriate
install -l invocations via new INSTALL_LINK and INSTALL_SYMLINK
variables.

Sponsored by: DARPA, AFRL
Reviewed by: ian, ray, rpaulo

Reimplementation of world/kernel build options. For details, see:

http://lists.freebsd.org/pipermail/freebsd-current/2006-March/061725.html

The src.conf(5) manpage is to follow in a few days.

Brought to you by: imp, jhb, kris, phk, ru (all bugs are mine)

Handle NO_INCS solely inside bsd.incs.mk.

Don't install includes if NO_TOOLCHAIN

Make sure the only thing that follows .endif or .else is a comment.

Try really hard to fix parallel installs. Add a bunch of .ORDER
directives to ensure that all realinstall sub-tasks are executed
after beforeinstall, similarly ensure that all afterinstall sub-
tasks are executed after realinstall. Demonstration:

all: task1 task2
.ORDER: task1 task2

task2: task2_subtask
.ORDER: task1 task2_subtask

task1 task2 task2_subtask:
@sleep `jot -r 1 0 1.0`
@echo ${.TARGET}

Without the second .ORDER directive, task2_subtask can be run in
parallel with task1.

Spotted by: Andrea Campi <andrea@webcom.it>

Rename `includes' to `buildincludes'.
Rename `incsinstall' to `installincludes'.
Make `includes' a -j safe shortcut for `buildincludes' + `installincludes'.
`buildincludes' and `installincludes' are SUBDIR friendly, if run directly.

Added new bsd.incs.mk which handles installing of header files
via INCS. Implemented INCSLINKS (equivalent to SYMLINKS) to
handle symlinking include files. Allow for multiple groups of
include files to be installed, with the powerful INCSGROUPS knob.
Documentation to follow.

Added standard `includes' and `incsinstall' targets, use them
in Makefile.inc1. Headers from the following makefiles were
not installed before (during `includes' in Makefile.inc1):

kerberos5/lib/libtelnet/Makefile
lib/libbz2/Makefile
lib/libdevinfo/Makefile
lib/libform/Makefile
lib/libisc/Makefile
lib/libmenu/Makefile
lib/libmilter/Makefile
lib/libpanel/Makefile

Replaced all `beforeinstall' targets for installing includes
with the INCS stuff.

Renamed INCDIR to INCSDIR, for consistency with FILES and SCRIPTS,
and for compatibility with NetBSD. Similarly for INCOWN, INCGRP,
and INCMODE.

Consistently use INCLUDEDIR instead of /usr/include.

gnu/lib/libstdc++/Makefile and gnu/lib/libsupc++/Makefile changes
were only lightly tested due to the missing contrib/libstdc++-v3.
I fully tested the pre-WIP_GCC31 version of this patch with the
contrib/libstdc++.295 stuff.

These changes have been tested on i386 with the -DNO_WERROR "make
world" and "make release".