- 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

WARNS=3'ify.

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

Sorry folks; I accidentally committed a patch from what I was working
on a couple of days ago. This should be the most recent changes.

Noticed by: davidxu

Add architecture dependent atomic ops (atomic_swap only), KSE specific
data, and userland versions of [gs]etcontext().

Modify the UTS entry and exit functions to account of FPU validity
and format.