[llvm] DAG: Handle lowering unordered compare with inf (PR #100378)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> @arsenm Are you happy with the legality check workaround to avoid the x87 regression? We could attempt a custom lowering if you'd prefer?

I think it's fine

https://github.com/llvm/llvm-project/pull/100378