[clang] [Flang][driver] Do not emit -latomic on link line on Windows (PR #164648)

[David Truby via cfe-commits]

DavidTruby wrote:

I haven't done anything special to turn on atomic support in compiler-rt and I can build and run at least simple programs using omp atomic and get the expected results. Not sure where I'm getting the symbols from.

Anyway, if this is just for lld-link lines we definitely shouldn't be adding this at all so LGTM!

https://github.com/llvm/llvm-project/pull/164648