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

[Andrzej Warzyński via cfe-commits]

https://github.com/banach-space approved this pull request.

LGTM, my final comment is nit - feel free to ignore. Thanks!

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