[clang] [clang] Add noipa attribute (PR #207502)

[Aaron Ballman via cfe-commits]

AaronBallman wrote:

Okay, thank you for the discussion! I think this swings me to being comfortable with `noipa` implying `noinline`; I don't think there's enough push-back on that idea to warrant an RFC, either.

https://github.com/llvm/llvm-project/pull/207502