[clang] [llvm] [OpenMP][Clang] Migrate OpenMP UserDefinedMapper from Clang to OMPIRBuilder (PR #110001)

[Jan Patrick Lehr via llvm-commits]

jplehr wrote:

Thank you. Will take a closer look next week.
So far, I ran this through one of our buildbot configs and did not see an issue there.

https://github.com/llvm/llvm-project/pull/110001