[llvm] [Transforms] Let amdgcn take advantage of sin(-x) --> -sin(x) (PR #79700)

[Matt Arsenault via llvm-commits]

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

This is the opposite of what we want for codegen, but I believe we undo this already 

https://github.com/llvm/llvm-project/pull/79700