Amongst other, this will help LTO to correctly handle/honor files
compiled with O0, helping debugging failures.
It also seems in line with how we handle other options, like how
-fnoinline adds the appropriate attribute as well.
Differential Revision: https://reviews.llvm.org/D28404
llvm-svn: 304127
lit.cfg has never supported running .C files, so these tests were never
executed by check-clang. Rename them to .cpp so that they run as part of
the test suite, and minorly tweak two of them that look like they were broken
when checked in to actually pass.
llvm-svn: 227029
Mehdi Amini