[OpenMP] Adding support to the mutexinoutset dep-type

[OpenMP] Adding support to the mutexinoutset dep-type

Summary: this commit adds support to a new dependence type introduced in OpenMP
5.0. The LLVM OpenMP RTL already supports this feature, so we  only need to
modify CLANG to take advantage of them.

Differential Revision: https://reviews.llvm.org/D57576

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@353018 91177308-0d34-0410-b5e6-96231b3b80d8