GH-131296: fix clang-cl warning on Windows in _wmimodule.cpp

[chris-eibl]

I think this is a skip news?

• Issue: clang-cl issues many warnings when building on Windows #131296

[chris-eibl]

fix warning : unused variable 'result' [-Wunused-variable]

[zooba]

@chris-eibl Just FYI, I'm rewriting a lot of your PR titles when we commit. It's not a problem - part of what we do as core devs - but you probably haven't noticed, so figured I'd mention it in case you wanted to check them.

It's unfortunate that they follow the PR title by default, because your PR titles are fine. But commit messages are more likely to be read without context (in this case, without timeliness - they'll be read in the future when there isn't a flurry of clang-cl warnings being dealt with), so we tend to go a bit more neutral with them.

[chris-eibl]

Yeah - sure. I am reading for quite some time here, so I am familiar with having modified commit messages when merging upstream - for exactly that reason. Big +1 from me :)