[llvm] [Transforms][Utils][PromoteMem2Reg] Propagate nnan flag on par with the nsz flag (PR #114271)

[Paul Osmialowski via llvm-commits]

pawosm-arm wrote:

I've rebased my PR so it could also contain phase-ordering test for vectorizing predicated selects introduced by commit 577c7dd7cc4c5a9f62f9654cfa30ee9d55709426

https://github.com/llvm/llvm-project/pull/114271