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

[Chris Copeland via llvm-commits]

chrisnc wrote:

CI is passing with no changes to existing tests. @davemgreen @ostannard @smithp35 please let me know if any further changes are needed. Having this backstop will give the users of other tools a chance at avoiding these situations.

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