In case further such cases appear in the future we've got a generic function to add them to.
Additionally changed the ObjC special case to check the language and the identifier builtin ID instead of the name.
Addresses the cleanup suggestion from D87917.
I'm pretty sure this builtin only exists in ObjC mode, so there's no need to separately check the language mode. (Even if you did want to check it, it would be better to check the builtin mode first, as that's a very trivial check.)