SDL: Fix software renderer build
SDL: Fix software renderer build

fr500/mgba,Iniquitatis/mgba,fr500/mgba,mgba-emu/mgba,Anty-Lemon/mgba,Anty-Lemon/mgba,mgba-emu/mgba,Iniquitatis/mgba,fr500/mgba,fr500/mgba,mgba-emu/mgba,libretro/mgba,Anty-Lemon/mgba,libretro/mgba,libretro/mgba,Iniquitatis/mgba,Anty-Lemon/mgba,libretro/mgba,mgba-emu/mgba,Iniquitatis/mgba,libretro/mgba