Qt: Add support for back key
Qt: Add support for back key

libretro/ppsspp-native,zhykzhykzhyk/ppsspp-native,hrydgard/native,libretro/ppsspp-native,unknownbrackets/native,unknownbrackets/native,unknownbrackets/native,hrydgard/native,zhykzhykzhyk/ppsspp-native,libretro/ppsspp-native,hrydgard/native,libretro/ppsspp-native,unknownbrackets/native,zhykzhykzhyk/ppsspp-native,zhykzhykzhyk/ppsspp-native,hrydgard/native