- 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

MFKernel: do not use __XSCALE__ to detect if clz/pld/ldrd/strd are
available, use _ARM_ARCH_5/_ARM_ARCH_5E instead.

MFC After: 3 days

Use the RET macro.
For setjmp() and longjmp(), put the signal mask where it's supposed to be,
instead of in the space reserved for fp regs.

Import the FreeBSD/arm libc bits.

Obtained from: NetBSD