[llvm] [Transforms] Resolve FIXME: No Lowering of FNeg to FMul unless it is safe (PR #85252)

[Matt Arsenault via llvm-commits]

arsenm wrote:

> which doesn't matter if it's only used by operations that canonicalize the inputs. 

I guess we technically don't guarantee canonicalization on FP operations, but I think we can assert that it may happen 

https://github.com/llvm/llvm-project/pull/85252