[llvm] [CloneFunction] Remove check that is no longer necessary (PR #92577)

[Nikita Popov via llvm-commits]

https://github.com/nikic approved this pull request.

It looks like InstSimplify only does constant folding for non-intrinsics, so probably the only way to hit this with upstream LLVM is if it's constant folding that involves a loop phi in some way and thus only happens late?

Given that, constructing a test case may be tricky, so I'm fine with landing it as-is.

https://github.com/llvm/llvm-project/pull/92577