[clang] [Sema] Check arg count for builtins with CustomTypeChecking (PR #222841)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

I think this is the right approach to take, but I also need a PPC expert to review to ensure the BCD intrinsic changes are correct (i32 vs i8). CC @hubert-reinterpretcast @amy-kwan (feel free to rope in other reviews if you think someone else is more appropriate).

https://github.com/llvm/llvm-project/pull/222841