Import Intel's Clang OpenMP patchset, rebased to Clang trunk.

This represents joint work by ALCF and Pathscale.
Revert VLA hack

This hack to support 1-D VLAs in captured regions is no longer needed (a better
solution should exist in the upstream clang-omp repository).
Restore CR_OpenMP

Support for CR_OpenMP should not be removed, it exists for better diagnostics.

Thanks to Alexey Bataev for pointing this out during code review.
Merge pull request #1 from hfinkel/master

Import Intel's Clang OpenMP patchset, rebased to Clang trunk.