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

[Yashwant Singh via llvm-commits]

yashssh wrote:

Out of curiosity what's the purpose of doing this? From one of the tests attached It just looks like we are moving `fneg` from before `sin` to after.

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