Fix wrong to linear conversion
Has +2, not merged yet.
Causing bad rendering of gamma corrected text on non-standard image
format paint devices.
Pick-to: 6.4 6.2 5.15
Fixes: QTBUG-109169
Change-Id: I6d95e9a42b9ccac609071123dd4535d25e225a29
Reviewed-by: Fabian Vogt <fabian@ritter-vogt.de>
Reviewed-by: Eirik Aavitsland <eirik.aavitsland@qt.io>
(cherry picked from commit a09c33e1f7b5999a16bce9dd23ef8ca33d519210)
Edited by Fabian Vogt