[clang] [AST] Bump Type::NumOfBuiltinTypeBits. NFCI. (PR #113559)

[Aaron Ballman via cfe-commits]

https://github.com/AaronBallman commented:

The community doesn't add new builtin types particularly often, so having four leftover bits isn't actually that close to the limit for us. Is there a problem with keeping this change downstream until we get to the limit in community?

https://github.com/llvm/llvm-project/pull/113559