- 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

Fix ixp425 boot2 with ARM EABI:
- libkern is missing __aeabi_llsl, implement this by calling __ashldi3.
- Because of how the asm entry macros are defined the boot2 code
requires the unwind symbols to exist, include them in boot2.

Approved by: re (marius)

Move the __aeabi_unwind_cpp_pr{0,1,2} functions to libkern so they can be
referenced in a non-debug kernel.