[llvm] [Statepoint] Return undef value for the statepoint of the none token (PR #72552)

[Nuno Lopes via llvm-commits]

nunoplopes wrote:

> @nunoplopes possibly. Not sure what semantics of this would be though. And this would need to be adapted to poison as well (otherwise there is no point): [d693fd2](https://github.com/llvm/llvm-project/commit/d693fd29f1885e72b90428999aee92573abb9c2d)

Right. It seems all of those could be converted to poison. It's being used just as a placeholder, so anything works.

https://github.com/llvm/llvm-project/pull/72552