[llvm] [CI] Disable Flang from pre-commit tests when Flang files are not touched on Windows Only (PR #93729)

[Renato Golin via llvm-commits]

rengolin wrote:

I don't know how that CI script works, but if that does what we wanted from #93485, then it should be fine to merge this and close the other.

https://github.com/llvm/llvm-project/pull/93729