[llvm] [LV] Apply urem folds to preheader (PR #213928)

[Ramkumar Ramachandra via llvm-commits]

artagnon wrote:

> Really, if we're manually editing files we should also remove the NOTE I think but that's just my opinion!

It's just some best-effort to unstage some hunks, to compensate for UTC's deficiencies -- I personally always try to do it, and don't mind if others don't, but just noting that it's maybe 30 mins of grunt work with the right tools for 100+ files?

https://github.com/llvm/llvm-project/pull/213928