SDL: Actually use FindSDL2 by default
SDL: Actually use FindSDL2 by default

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