[OPENMP50]Register vendor name only once in vendor context selector.

No need to store multiple copies of the same vendor names in the context
selector, keep only single copy.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@374363 91177308-0d34-0410-b5e6-96231b3b80d8
3 files changed