[clang] [driver] mark offload.f90 as REQUIRES: openmp_runtime (PR #181759)

[Henrik G. Olsson via cfe-commits]

hnrklssn wrote:

In our downstream repo the test case fails with `error: unsupported option '-fopenmp'`. This was the only REQUIRES feature related to OpenMP I could find, but if it's not appropriate for this test case I can manually disable the test downstream instead.

https://github.com/llvm/llvm-project/pull/181759