[compiler-rt] [compiler-rt] [test] Generalize an UNSUPPORTED marking (PR #168858)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

> These have now been marked unsupported for all platforms here: https://github.com/llvm/llvm-project/pull/168821/files.

Thanks! But as long as the test is still in place, I'll go ahead and merge this, so the issue doesn't reappear if the `UNSUPPORTED: true` is removed again later.

https://github.com/llvm/llvm-project/pull/168858