[llvm] [openmp] Remaining work necessary for GCC 15 (PR #157385)

[Michael Kruse via llvm-commits]

Meinersbur wrote:

The PR summary still reads
> Fully disable glibc assertions for OpenMP runtime.

please update and add more details, including in the PR title. "remaining work" presumes having followed the progress of "work", which very few people have.

https://github.com/llvm/llvm-project/pull/157385