[clang] [Clang][Driver] Override complex number calculation method by -fno-fa… (PR #132680)

[Andy Kaylor via cfe-commits]

andykaylor wrote:

@s-watanabe314 I apologize for the very long delay in responding. This fell off my radar for a while.

I think your latest proposed handling of warnings looks good, but I'd like to see input from @MaskRay also.

https://github.com/llvm/llvm-project/pull/132680