Copy head (r256279) to stable/10 as part of the 10.0-RELEASE cycle.

Approved by: re (implicit)
Sponsored by: The FreeBSD Foundation

Work around an ARM EABI issue where clang would sometimes incorrectly align
the stack in a leaf function that uses TLS.

The issue is, when using TLS, the function is no longer a leaf as it calls
__aeabi_read_tp. With statically linked programs this is not an issue as
it doesn't make use of the stack, however with dynamically linked
applications we enter rtld which does use the stack and makes assumptions
about it's alignment.

This is only a temporary fix until a better patch can be made and submitted
upstream.

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

Upgrade our copy of llvm/clang to r130700, from upstream's trunk.

Upgrade our copy of llvm/clang to r126079, from upstream's trunk.

This contains many improvements, primarily better C++ support, an
integrated assembler for x86 and support for -pg.

Vendor import of llvm trunk r126079:
http://llvm.org/svn/llvm-project/llvm/trunk@126079