[llvm] [DFAJumpThreading] Unify equivalent states (PR #162447)

[Hongyu Chen via llvm-commits]

XChy wrote:

New compile-time number: https://llvm-compile-time-tracker.com/compare.php?from=f62d9537b334cbb91ffb7569d543a5f87aa4a165&to=1be6b62b8cddc7b8587902b7ce2c05b05c567046&stat=instructions%3Au

https://github.com/llvm/llvm-project/pull/162447