OpenGL: Clean up freed and detached shaders a bit more
OpenGL: Clean up freed and detached shaders a bit more

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