[llvm] [VPlan] Set flags when constructing zexts using VPWidenCastRecipe (PR #164198)

[Ramkumar Ramachandra via llvm-commits]

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

Looks like the memchecks and scev-checks are gone, so this LGTM, thanks!

https://github.com/llvm/llvm-project/pull/164198