- 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

Upgrade our copy of llvm/clang to r155985, from upstream's release_31
branch. This brings us very close to the 3.1 release, which is planned
for May 14th.

MFC after: 2 weeks

Vendor import of llvm release_31 branch r155985:
http://llvm.org/svn/llvm-project/llvm/branches/release_31@155985