- Copy stable/10 (r259064) to releng/10.0 as part of the
10.0-RELEASE cycle.
- Update __FreeBSD_version [1]
- Set branch name to -RC1

[1] 10.0-CURRENT __FreeBSD_version value ended at '55', so
start releng/10.0 at '100' so the branch is started with
a value ending in zero.

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

Replace the assembler macro WEAK_ALIAS with a new macro WEAK_REFERENCE which
has the same API as __weak_reference(). Give 'x' in SYS.h a more meaningful
name.

Tested on 32- and 64-bit PowerMac.

Reviewed by: bde

Two other places where we can use WEAK_ALIAS.

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)