fix problem with menus freezing on 3DS

[camthehaxman]

Entering some menus on 3DS while in-game will end up freezing the entire console when C3D_FrameBegin is called, and there doesn't appear to be any rhyme or reason for why this happens. Apparently using gspWaitForVBlank for vsync instead of passing the C3D_FRAME_SYNCDRAW flag to C3D_FrameBegin fixes the freezing issue. Note that if the user intentionally disables VSync, then the freezing issue will still occur.

[UnknownShadow200]

a03d1d7a13b9b2e99446cf339d19de40bc2d06e6 should fix this