The gesture system was not handling the case when all touch points are released (pointCount == 0), causing GESTURE_NONE to never be reported on Android.

This adds an else if block in ProcessGestureEvent() to handle pointCount == 0 and properly reset the gesture state to GESTURE_NONE.

Fixes issue #5010 where GetGestureDetected() would not return GESTURE_NONE after all touch points were released.

Now it goes from -1.0 (full left) to 1.0 (full right) being 0.0 center