* Replace max_step_search_steps with constant MAX_MVSEARCH_STEPS
* Fold (reduce_first_step_size + speed > 5) into reduce_first_step_size
  replacing uses of reduce_first_step_size that don't add the speed
  check with zero.

Change-Id: Iae46395dbf3eaca138bf4d18b838a9e364b5a198