Hinted lock (OpenMP 4.5 feature) Updates/Fixes

There are going to be two more patches which bring this feature up to date and in line with OpenMP 4.5.

* Renamed jump tables for the lock functions (and some clean up).
* Renamed some macros to be in KMP_ namespace.
* Return type of unset functions changed from void to int.
* Enabled use of _xebgin() et al. intrinsics for accessing TSX instructions.

Differential Revision: http://reviews.llvm.org/D15199

llvm-svn: 255373