[clang] [flang] [flang][driver] Make -stdlib= option visible to flang and silently ignored by it (PR #110598)

[David Truby via cfe-commits]

DavidTruby wrote:

Sorry I wasn’t very clear in my previous comments; I think we shouldn’t go ahead with this PR and should continue to reject the flag. So I think we’re in agreement.

https://github.com/llvm/llvm-project/pull/110598