[llvm] [ConstraintElimination] Add eq/ne facts to signed constraint system (PR #121423)

[Nikita Popov via llvm-commits]

https://github.com/nikic commented:

Compile-time: http://llvm-compile-time-tracker.com/compare.php?from=193ea83dd7e879ddd4e3dfb1fa74a676b528e4a6&to=b4b2d9643dfef63550aecaea008ece92c549247f&stat=instructions:u

https://github.com/llvm/llvm-project/pull/121423