- Copy stable/10@285827 to releng/10.2 in preparation for 10.2-RC1
builds.
- Update newvers.sh to reflect RC1.
- Update __FreeBSD_version to reflect 10.2.
- Update default pkg(8) configuration to use the quarterly branch.[1]

Discussed with: re, portmgr [1]
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

Do not restore the register holding the TLS pointer when doing various
usermode context switches (long jumps and ucontext operations). If these
are used across threads, multiple threads can end up with the same TLS base.
Madness will then result.

This makes behavior on PPC match that on x86 systems and on Linux.

MFC after: 10 days

Mark assembler sources from libc as working with non-executable stack.

Reviewed and tested by: nwhitehorn

Minimal libc for PowerPC.

Reviewed by: benno

Approved by: re (blanket)