- Copy stable/10@296371 to releng/10.3 in preparation for 10.3-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.3.
- Update default pkg(8) configuration to use the quarterly branch.

Approved by: re (implicit)

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

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

Merge from tbemd:

Convert from using MACHINE_ARCH to MACHINE_CPUARCH. Hoist path statement
up into the top Makefile rather than repeating it on every arch Makefile.

WARNS=3'ify.

Fix a race condition introduced when redzones were added. Use an
atomic operation to return and adjust the stack.

Submitted by: luoqi

Cosmetic tweaks to reduce diffs to the i386 counterpart.

gcc -O2 cleanup. tested for a long time.

Reviewed by: deischen

1. Add macro DTV_OFFSET to calculate dtv offset in tcb.
2. Export symbols needed by debugger.

Add TLS support for i386 and amd64.

Save context in kernel fashion, so it can be restored by
kse_switchin syscall.

Remove unused field.

Macro optimize, this increases context switch speed about 2% on my
athlon64 machine.

Call kse_switchin to switch context when being debugged.

Avoid clobbering the red zone when running on the new context's stack in
_amd64_restore_context().

Apply a second fix for stack alignment with libkse. This time, enter the
UTS with the stack correctly aligned. Also, while here, use an indirect
jump rather than the pushq/ret hack.

This fixes threaded apps that use floating point for me, although
it hasn't solved all the problems. It is an improvement though.
Preservation of the 128 byte red zone hasn't been resolved yet.

Approved by: re (scottl)

Use amd64_set_fsbase() instead of calling sysarch() directly.

Update context code for my last ABI breakage of mcontext. I'm worried
about the fpu code here. It should be using fxsave/fxrstor instead of
saving/restoring the control word. The SSE registers are used a lot in
gcc generated code on amd64. I'm not sure how this all fits together
though.

Make KSE_STACKSIZE machine dependent by moving it from thr_kern.c to
pthread_md.h. This commit only moves the definition; it does not
change it for any of the platforms. This more easily allows 64-bit
architectures (in particular) to pick a slightly larger stack size.

Remove a comment that questioned why the size of the FPU
state for amd64 was twice as large as necessary. Peter
recently fixed this, so the comment no longer applies.

Also, since the size of struct mcontext changed, adjust
the threads library version of get&set context to match.

FYI, any change layout/size change to any arch's struct
mcontext will likely need some minor changes in libpthread.

Don't assume sizeof(long) = sizeof(int) on x86; use int
instead of long types for low-level locks.

Add prototypes for some internal libc functions that are
wrapped by the library as cancellation points.

Add memory barriers to alpha atomic swap functions (submitted
by davidxu).

Requested by: bde

Don't forget to set kcb_self.

Rethink the MD interfaces for libpthread to account for
archs that can (or are required to) have per-thread registers.

Tested on i386, amd64; marcel is testing on ia64 and will
have some follow-up commits.

Reviewed by: davidxu

-15 is incorrect to be used to align stack to 16 bytes, use ~15 instead.

Fix some typos, correctly jump into UTS.

Fix typo.

Add missing arguments to _amd64_restore_context() when called from
THR_SETCONTEXT().

Add some very beta amd64 bits. These will also need some tweaking.