[clang-cl] Accept /FA[c][s][u], but ignore the arguments

Previously, /FAsc would emit a warning. Now, it will just do what /FA does.

https://docs.microsoft.com/en-us/cpp/build/reference/fa-fa-listing-file?view=msvc-170

Reviewed By: hans

Differential Revision: https://reviews.llvm.org/D127519