[clang] [flang] [flang] Preserve fixed form in fc1 -x value (PR #117563)

[David Truby via cfe-commits]

DavidTruby wrote:

Thanks for the fix, I'd like to understand what the bug is better though; what is the difference between the proposed `flang -fc1 -x f95-fixed` and the existing `flang -fc1 -ffixed-form`? 
In the test case in here I already don't see an error with `flang -fc1 -ffixed-form`, is there an example you have where this fails to compile but `-x f95-fixed` works?

https://github.com/llvm/llvm-project/pull/117563