[llvm] [LV][EVL] Support in-loop reduction using tail folding with EVL. (PR #90184)

[Florian Hahn via llvm-commits]

https://github.com/fhahn commented:

A few more comments inline, but after that I think this should be good to go!

(It looks like a few tests might need updating when updating to latest main)

https://github.com/llvm/llvm-project/pull/90184