INT 62 u - FGDRIVER v3.03 - "FG_BUTTON" - GET JOYSTICK BUTTON STATE
        AX = 0009h
        BX = joystick number (0001h or 0002h)
Return: AX = button states
            bit 0: top button pressed
            bit 1: bottom button pressed
Note:   For FGDRIVER v1.10, this function was unused; "FG_BUTTON" was AX=0078h
SeeAlso: AX=0044h,AX=0046h,AX=004Dh,AX=0050h,AX=0061h

.