nce_add_impl
static nce_t *nce_add_impl(ill_t *, ncec_t *, nce_t *, mblk_t *, list_t *);
*retnce = nce_add_impl(ill, ncec, nce, dlur_mp, &graveyard);
return (nce_add_impl(ill, ncec, nce, dlur_mp, graveyard));