[llvm] Spaceship intrinsic for GSoC 2024 (PR #83227)

[Miguel Raz Guzmán Macedo via llvm-commits]

miguelraz wrote:

@dtcxzyw gladly! I think it makes sense to split it after completing Stage 2 and landing support in SelectionDAG for the `ThreeWayCmp`. Does that seem reasonable?

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