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 trunk r178860, in preparation of the
upcoming 3.3 release (branching and freezing expected in a few weeks).

Preliminary release notes can be found at the usual location:
<http://llvm.org/docs/ReleaseNotes.html>

An MFC is planned once the actual 3.3 release is finished.

Upgrade our copy of llvm/clang to trunk r154661, in preparation of the
upcoming 3.1 release (expected in a few weeks). Preliminary release
notes can be found at: <http://llvm.org/docs/ReleaseNotes.html>

MFC after: 2 weeks

Revive the LLVM and Clang license files, which were removed in my
too-thorough cleanup of unused files, in r213695. Also make sure these
get installed under /usr/share/doc.

Submitted by: rwatson, brooks
Pointy hat to: dim
MFC after: 3 days

Vendor import of clang trunk r135360:
http://llvm.org/svn/llvm-project/cfe/trunk@135360

Update clang to r93512.

Update clang to r84119.

Import Clang, at r72732.