[clang] [llvm] [OpenMP][OMPIRBuilder] Handle non-failing calls properly (PR #115863)

[Sergio Afonso via cfe-commits]

skatrak wrote:

Thank you @Meinersbur for your comments. I just updated the PR description and replaced `cantFail()` calls in unit tests as you suggested, let me know if that addresses your concerns.

https://github.com/llvm/llvm-project/pull/115863