[llvm] [InstCombine] Avoid DeMorgan's on occasion (PR #109215)

[Craig Topper via llvm-commits]

topperc wrote:

Preventing the transform in InstCombine only solves the problem if the user was aware of the existence of andn and wrote their code as `s &= ~(z & ~y)`. A user unaware of `andn` might write `s &= ~z | y` in their code because it looks simpler.

https://github.com/llvm/llvm-project/pull/109215