Fix OMP_TARGET_OFFLOAD parsing

Current parsing allows trailing string after the permitted value,
MANDATORY|DISABLED|DEFAULT -- e.g., "mandatorynot" is also recognized
as "MANDATORY". Such cases should be recognized as incorrect/unknown
value.

Differential Revision: https://reviews.llvm.org/D62431


git-svn-id: https://llvm.org/svn/llvm-project/openmp/trunk@362125 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed