[clang] [llvm] [OpenMP][clang] Set num_threads 'strict' to unsupported on GPUs (PR #160659)

[Joseph Huber via llvm-commits]

jhuber6 wrote:

We emit warnings for stuff like `#pragma omp simd` on the GPU, which is also unsupported. Probably best to keep this as a warning.

https://github.com/llvm/llvm-project/pull/160659