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

Fix build when WITH_SSP is set explicitly.

Submitted by: Jeremie Le Hen

Enable GCC stack protection (aka Propolice) for userland:
- It is opt-out for now so as to give it maximum testing, but it may be
turned opt-in for stable branches depending on the consensus. You
can turn it off with WITHOUT_SSP.
- WITHOUT_SSP was previously used to disable the build of GNU libssp.
It is harmless to steal the knob as SSP symbols have been provided
by libc for a long time, GNU libssp should not have been much used.
- SSP is disabled in a few corners such as system bootstrap programs
(sys/boot), process bootstrap code (rtld, csu) and SSP symbols themselves.
- It should be safe to use -fstack-protector-all to build world, however
libc will be automatically downgraded to -fstack-protector because it
breaks rtld otherwise.
- This option is unavailable on ia64.

Enable GCC stack protection (aka Propolice) for kernel:
- It is opt-out for now so as to give it maximum testing.
- Do not compile your kernel with -fstack-protector-all, it won't work.

Submitted by: Jeremie Le Hen <jeremie@le-hen.org>

Respect MK_INET6_SUPPORT.

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)

Respect the YES_HESIOD build variable.

Add knob NO_NIS (fka NO_YP_LIBC) and make world compileable when set.
If turned on no NIS support and related programs will be built.

Lost parts rediscovered by: Danny Braniss <danny at cs.huji.ac.il>
PR: bin/68303
No objections: des, gshapiro, nectar
Reviewed by: ru
Approved by: rwatson (mentor)
MFC after: 2 weeks

For variables that are only checked with defined(), don't provide
any fake value.

*major* style problems.

We don't need so many -I's.

Don't directly use GCC warnings.

Add /rescue bits. This basically encompasses all of bin and sbin along
with a couple of bits from usr.bin in a crunchgen'd binary.

Submitted by: Tim Kientzle <kientzle@acm.org>