Fun fact: Mutexes is not multi-threading. Mutex locks are the opposite of multi-threading!
Bicker!!!
Bicker bicker bicker!!! Are you saying that c++11 is more widely supported than c? Bicker? Stuff, bicker. Nonsense! Bicker!!
P.S. Anyway, I guess newer gcc can use "__atomic*" prefix...? But clang uses "__sync*" ? ..Whatever. AFAICT they cover windows and unix toolchains so there's probably no issues there.
[edit] Keep in mind that the allegro.cc folks like to argue about anything and everything. At least that's what happened every time I used to stop by there.