The alpha channel of an RGB32 image was not properly ignored when doing
blending with partial opacity.
Now the alpha value is properly ignored, which is both more correct
and faster. This also makes SSE2 and AVX2 implementations match NEON
which was already doing the right thing (though had dead code for
doing it wrong).
Change-Id: I4613b8d70ed8c2e36ced10baaa7a4a55bd36a940
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
e3b6f6d165