[llvm] [SystemZ, LoopVectorizer] Enable vectorization of epilogue loops after VF16. (PR #172925)

[Florian Hahn via llvm-commits]

https://github.com/fhahn approved this pull request.

LGTM with a two more comments addressed + formatting fixed.

Please also update the PR title to reflect the latest version of the code

https://github.com/llvm/llvm-project/pull/172925