[OPENMP50]Suppport for multiple vendors in the same vendor context
selector.

According to OpenMP 5.0, multiple vendors could be specified in the
vendor context selector via ',' as a separator.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@373756 91177308-0d34-0410-b5e6-96231b3b80d8
5 files changed