[llvm] [InstCombine] Copy nsw if it is present on the neg when folding `abs(-x)` -> `abs(x)` (PR #81496)

[Nikita Popov via llvm-commits]

nikic wrote:

This PR is broken on so many levels, it's not even funny. I have no interest in baby-sitting it to an acceptable state.

https://github.com/llvm/llvm-project/pull/81496