[llvm] [SCEV] Strengthen flags for AddRec post-inc (PR #217437)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

Small compile-time improvement: https://llvm-compile-time-tracker.com/compare.php?from=2d697458ac3f472e666b7f47586da362839cfacb&to=aeb103579db724b8a640c9a92d6377cddbf3d58e&stat=instructions:u

https://github.com/llvm/llvm-project/pull/217437