minor tweaks to the smartlist operations

void smartlist_add(smartlist_t *sl, void *element) {

  if(sl->num_used < sl->max)

    sl->list[sl->num_used++] = element;

  else

    log_fn(LOG_WARN,"We've already got %d elements, discarding.",sl->max);

}

void smartlist_remove(smartlist_t *sl, void *element) {

  int i;

  if(element == NULL)

    return;

  for(i=0; i < sl->num_used; i++)

    if(sl->list[i] == element)

    if(sl->list[i] == element) {

      sl->list[i] = sl->list[--sl->num_used]; /* swap with the end */

      i--; /* so we process the new i'th element */

    }

}

void *smartlist_choose(smartlist_t *sl) {