[llvm] [Attr] Add `noipa` function attribute (PR #203304)

[J. Ryan Stinnett via llvm-commits]

jryans wrote:

> AI-generated test cases that apparently still optimize under noipa + noinline.

Aha, interesting, thanks... I'll take a look at these cases as well.

https://github.com/llvm/llvm-project/pull/203304