HEADS UP: Upgraded clang, llvm and lldb to 3.5.0

Hi,

I just committed an upgrade of clang, llvm and lldb to 3.5.0 to head, in
r276479.

Please note that this version now requires C++11 support to build; see
UPDATING for more information.

Release notes for llvm and clang can be found here:
<http://llvm.org/releases/3.5.0/docs/ReleaseNotes.html>
<http://llvm.org/releases/3.5.0/tools/clang/docs/ReleaseNotes.html>

Thanks to Ed Maste, Roman Divacky, Andrew Turner, Justin Hibbits and
Antoine Brodin for their invaluable help with this import.

-Dimitry