Qt: Fix remaining write to drawContext
Qt: Fix remaining write to drawContext

jeremyherbert/mgba,Anty-Lemon/mgba,Touched/mgba,Touched/mgba,Iniquitatis/mgba,MerryMage/mgba,sergiobenrocha2/mgba,Iniquitatis/mgba,sergiobenrocha2/mgba,mgba-emu/mgba,jeremyherbert/mgba,MerryMage/mgba,Iniquitatis/mgba,Anty-Lemon/mgba,AdmiralCurtiss/mgba,sergiobenrocha2/mgba,iracigt/mgba,AdmiralCurtiss/mgba,sergiobenrocha2/mgba,jeremyherbert/mgba,Anty-Lemon/mgba,mgba-emu/mgba,fr500/mgba,iracigt/mgba,fr500/mgba,sergiobenrocha2/mgba,libretro/mgba,AdmiralCurtiss/mgba,iracigt/mgba,iracigt/mgba,libretro/mgba,libretro/mgba,fr500/mgba,Iniquitatis/mgba,MerryMage/mgba,fr500/mgba,libretro/mgba,mgba-emu/mgba,mgba-emu/mgba,libretro/mgba,Touched/mgba,Anty-Lemon/mgba,jeremyherbert/mgba