[clang] [clang] atomic fetch op misbehaves on atomic bool (PR #186940)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

Apologies on the review delay, this fell pretty far off my radar for a while it seems! I think this is actually pretty close to ready, though I did spot something in the C standard we're not yet covering.

Please be sure to also add a release note to `clang/docs/ReleaseNotes.rst`.

https://github.com/llvm/llvm-project/pull/186940