Make the speed control menu an optional build item.  Works fine; however...

..., seems pointless since Sailfish produces very fine quality at all speeds and doesn't have issues with the acceleration planner queue running dry in regions of fine detail owing to having an accel planner which is 5x faster than Marlin since it doesn't use floating point math.  And then another 2x speedup when fed accelerated move commands with some key data pre-computed.  To enable the speed control menu, uncomment the #define SPEED_CONTROL in Configuration.hh