Fix ImageMagick package build errors.

[acolwell]

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PR Description

What type of PR is this? (Check one of the boxes below)

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (non-breaking change which does not add functionality nor fixes a bug but improves Natron in some way)
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• My change requires a change to the documentation
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What does this pull request do?

Recently mingw changed the signature for wstat() in a way that started causing compiler errors. This change simply removes a previous fix related to wstat() added last year. It appears to no longer be needed and its removal fixes the current build error.

Have you tested your changes (if applicable)? If so, how?

Yes. Verified build package repo action builds successfully

[acolwell]

I'm going to commit this despite the Windows Test CI failing because that failure appears to be an unrelated clang issue that I haven't quite tracked down yet. Landing this will at least allow my pacman repo nightly to start working again.