[llvm] [LangRef][IR] Add 3-way compare intrinsics llvm.scmp/llvm.ucmp (PR #83227)

[Miguel Raz Guzmán Macedo via llvm-commits]

miguelraz wrote:

ping for @scottmcm and @dc03-work for review in case the other notifications drowned it out.

https://github.com/llvm/llvm-project/pull/83227