Convert the following uses:

netinet/ip_input.c:     m = m_get(MB_DONTWAIT, MT_HEADER);
netinet/sctp_usrreq.c:          m = m_get(MB_WAIT, MT_DATA);
netinet6/ip6_output.c:  *mp = m_get(MB_WAIT, MT_HEADER);                /* XXX */
netproto/ncp/ncp_rq.c:          m = m_get(MB_WAIT, MT_DATA);

Sizes must be programatically determined for the first argument to m_getb, if it is non-obvious a comment should be added above the call to m_getb briefly explaining what is to be put into the mbuf.