[clang] [CLANG] Enable alignas after GNU attributes (PR #133107)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

Thanks for the fix! The changes should come with a release note in `clang/docs/ReleaseNotes.rst` so users know about the fix.

https://github.com/llvm/llvm-project/pull/133107