[clang] [llvm] [ARM] Emit an error when the hard-float ABI is enabled but can't be used (PR #111334)

[Peter Smith via cfe-commits]

https://github.com/smithp35 commented:

I think I'm down to one suggestion for not using a friend as it looks like we can use a free function instead. That is more personal preference though so if it turns out to be a pain we can keep the friend.

Otherwise this is looking good to me. Thanks for all the hard work in updating the tests.

https://github.com/llvm/llvm-project/pull/111334