We can not use the same blend routines for ARGB32 as we use for
ARGB32PM. It needs to blend transparent colors differently.
Pick-to: 6.5
Fixes: QTBUG-91262
Change-Id: I6b75fa8096b92452655dcad94478ae2a74415939
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
(cherry picked from commit bb854606ec8f95787dfd2a4d1b6bcaddbcf4d042)
Reviewed-by: Qt Cherry-pick Bot <cherrypick_bot@qt-project.org>