[llvm] [InstCombine] fold `(icmp eq/ne (or disjoint x, C0), C1)` -> `(icmp eq/ne x, C0^C1)` (PR #87734)

[via llvm-commits]

AtariDreams wrote:

Given how the test cases show variables and not just constants, can this fold apply to variables too? 

https://github.com/llvm/llvm-project/pull/87734