3DS: Reuse screenshot buffer, cleanup
3DS: Reuse screenshot buffer, cleanup

mgba-emu/mgba,Iniquitatis/mgba,libretro/mgba,libretro/mgba,mgba-emu/mgba,Iniquitatis/mgba,mgba-emu/mgba,libretro/mgba,Iniquitatis/mgba,libretro/mgba,libretro/mgba,mgba-emu/mgba,Iniquitatis/mgba