[llvm] [Clang][OpenMP][OMPIRBuilder] Move Clang's OpenMP Member/MemberOf flag helpers into the OMPIRBuilder (PR #67844)

[via llvm-commits]

agozillon wrote:

Thank you all very much, I'll land this on Tuesday afternoon/evening provided no one has anything else to add in the time between. And I'll see what I can do about adding an OpenMPIRBuilderTest.cpp to the patch. 

https://github.com/llvm/llvm-project/pull/67844