Fix SetFileAttributes behavior for memfs sample

[nikola-sh]

Fixes issue that SetFileAttributes(..., FILE_ATTRIBUTE_NORMAL) can clean attributes prohibited to clean, for example, FILE_ATTRIBUTE_DIRECTORY . See SetFileAttributesW documentation.

Checklist

• [x] My code follows the style guidelines of this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the existing documentation
• [x] My changes generate no new warnings
• [ ] I have updated the change log (Add/Change/Fix)
• [x] I have cleaned up the commit history (use rebase and squash)

Changes proposed in this pull request:

• Operate on allowed attributes only
• Remove incorrect behavior in case fileattributes == 0
• Rework incorrect condition (fileattributes & (fileattributes - 1))

[Liryna]

Thanks @nikola-sh for reporting the issue and directly providing a pull request! Very appreciated! 🏆 Sorry for the delay