Also updates sve-fp.ll to use fneg directly.
Nit: These changes should probably go in with a standalone patch, but seem harmless enough to be included with this one.
@arsenm Also, there's an ongoing project to stop FMUL(-1.0, X)->FNEG(X) transformations when denormals are present, so this is a good change.
Just noticed a typo here:
Should say "when denormals are flushed".