[OpenMP] Thread limit is (sometimes) ignored

[jdoerfert]

We run this

int main() {
  int n = 1 << 20;
  int th = 12;
  int te = n / th;
#pragma omp target
#pragma omp teams loop num_teams(te), thread_limit(th)
  for (int i = 0; i < n; i++) {
  }
  return 0;
}

with 256 threads on AMD because we do not recognize the thread_limit clause.

[llvmbot]

@llvm/issue-subscribers-openmp

[llvmbot]

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