- 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.

Eliminate plt relocation for kse_switchin.

The caller is expected to set up PIC register corectly before
jumping to .cerror. This means .cerror has to be present in the
same module with its consumers, or bad things will happen.

Rethink the way thr_libc.So is generated. Relying on GCC to extract
only needed symbols from libc_pic is not working on sparc64.

Requested by: jake

Allow gcc driver to process -r option iself, do not use -Wl,-r to
bypass it. Doing otherwise did not allow compiler to detect and disable
conflicting options generated from specs.

Reported by: jake

Style.

Take thr_support.c out of SRCS so that it does not end up in libraries.
Record the missing dependency of thr_libc.So on the libc_pic.a library.

OK'ed by: kan

Don't force -L/usr/lib. This is incorrect because we should not be
looking at the host environment for anything. This breaks building
-CURRENT on 4.x as well.

Submitted by: kan@

Attempt to eliminate PLT relocations from rwlock aquire/release
path, making them suitable for direct use by the dynamic loader.

Register libpthread-specific locking API with rtld on startup.

This still has some rough edges with signals which should be
addresses later.

Approved by: re (scottl)