[Bug objc/66367] Objective-C Variadic Method Not Compiling

[chrisloonam at gmail dot com]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=66367

--- Comment #2 from Chris Loonam <chrisloonam at gmail dot com> ---
I think that being able to use `id` as an argument to va_arg is the expected
behavior, not an extension provided by the compiler.