If LLVM_DEFAULT_TARGET_TRIPLE is a non-darwin triple, the file might
fail. This might allow us to take out the FIXME and REQUIRES lines, but I'd
rather let the bots double-check that the test is ok first.
FYI, I had added -target in this test in r296263 but it was still failing for some reason in some bots, that's why I then switched to triple via r296265.
I'm not sure if it's going work now or not for all bots, but it does, that is definitely better.