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

Assume a big-endian default on MIPS and drop the "eb" suffix from MACHINE_ARCH.
This makes our naming scheme more closely match other systems and the
expectations of much third-party software. MIPS builds which are little-endian
should require and exhibit no changes. Big-endian TARGET_ARCHes must be
changed:
From: To:
mipseb mips
mipsn32eb mipsn32
mips64eb mips64

An entry has been added to UPDATING and some foot-shooting protection (complete
with warnings which should become errors in the near future) to the top-level
base system Makefile.

sysinstall was removed from usr.sbin/Makefile in r225937. Because per-arch
Makefiles were split out in this directory and others in userland, it makes it
quite easy to miss per-arch conditionals when changing something generally.

Fix n32 compile.

These changes are needed to fix n32 compile after the recent change of
mips n32 MACHINE_ARCH to mipsn32eb/mipsn32el.

Reviewed by: imp, bz (earlier version)

Retire TARGET_ABI.

Implement MACHINE_ARCH=mips64e[lb] to build N64 images. This replaces
MACHINE_ARCH=mipse[lb] TARGET_ABI=n64.

MACHINE_ARCH=mipsn32e[lb] has been added, but currently requires
WITHOUT_CDDL due to atomic issues in libzfs. I've not investigated
this much, but implemented this to preserve as much of the TARGET_ABI
functionality that I could. Since its presence doesn't affect the
working cases, I've kept it in for now.

Added mips64e[lb] to make universe, so more kernels build.

And I think this (finally) closes the curtain on the tbemd tree.

Merge from tbemd: use Makefile.arch to control building.

Reviewed by: arch@ (many times, no objection)