[clang] [flang] [flang][Driver] Support -print-supported-cpus and associated aliases (PR #117199)

[Andrzej Warzyński via cfe-commits]

https://github.com/banach-space commented:

Thanks, makes sense. From what I can tell, the behaviour is consistent with Clang (i.e. `-print-supported-cpus` invalidates any other action flags).

Just a couple of smallish comments/suggestions

https://github.com/llvm/llvm-project/pull/117199