rn_new_radix_mask
if ((*mp = m = rn_new_radix_mask(x, 0)))
*mp = rn_new_radix_mask(tt, *mp);
*mp = m = rn_new_radix_mask(x, NULL);
*mp = rn_new_radix_mask(tt, *mp);
static struct radix_mask *rn_new_radix_mask(struct radix_node *,