[Bug c/68966] atomic_fetch_* on atomic_bool not diagnosed

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=68966
--- Comment #4 from Martin Sebor <msebor at gcc dot gnu.org> ---
Patch posted for review:
https://gcc.gnu.org/ml/gcc-patches/2015-12/msg02075.html