m_act
#if (BSD >= 199306) && !defined(m_act)
(m)->m_act = 0; \
(ifq)->ifq_tail->m_act = m; \
(m)->m_act = (ifq)->ifq_head; \
if (((ifq)->ifq_head = (m)->m_act) == 0) \
(m)->m_act = 0; \
if (((ifq)->ifq_head = (m)->m_act) == 0) \
(m)->m_act = 0; \