[llvm] [llvm-windres] Change the interpretation of --preprocessor to match Binutils 2.36 (PR #75391)

[Martin Storsjö via llvm-commits]

mstorsjo wrote:

This goes on top of https://github.com/llvm/llvm-project/pull/75390 - only the topmost commmit should be reviewed in this PR.

CC @mati865 @lazka @pbo-linaro

https://github.com/llvm/llvm-project/pull/75391