[llvm] [InstCombine] Regard zext nneg as sext when folding add(zext neg(add)) (PR #88887)

[via llvm-commits]

XChy wrote:

This patch lacks alive2 proof, tests, and so on.
Please read about https://llvm.org/docs/InstCombineContributorGuide.html

https://github.com/llvm/llvm-project/pull/88887