[llvm] [SimplifyCFG] handle monotonic wrapped case for D150943 (PR #65882)

[via llvm-commits]

DianQK wrote:

> We ran into this on Fuchsia, which builds using tip-of-tree rustc. Once this is merged, can we get it added to the `llvmorg-17.0.0-rc4` tag, or a new release candidate tag that I can pull the fix back up into rust?

Bug fixes are always welcome. If you want to understand the process, refer to https://m.youtube.com/watch?v=onaNb2U1Od8.

https://github.com/llvm/llvm-project/pull/65882