[clang] Thread Safety Analysis: Fix implicit member access in attributes (PR #194457)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman approved this pull request.

Thank you! LGTM though this should have a release note in `clang/docs/ReleaseNotes.rst` so users know about the fix.

https://github.com/llvm/llvm-project/pull/194457