[llvm] [X86,SimplifyCFG] Use passthru to reduce select (PR #108754)

[Phoebe Wang via llvm-commits]

phoebewang wrote:

> I prefer to do this simplification in InstCombine: [712b8f6](https://github.com/llvm/llvm-project/commit/712b8f604f4184fbe615d70cae22d49687c42f82).
> 
> @nikic @KanRobert Any thoughts?

I found it's not difficult to solve above crash. But I'm open to either way.

https://github.com/llvm/llvm-project/pull/108754