Qt: Fix Library crashing if the MRU is empty (fixes #746)
Qt: Fix Library crashing if the MRU is empty (fixes #746)

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