proto_Prepend
bp = proto_Prepend(bp, fp->proto, 0, 0);
bp = m_pullup(proto_Prepend(bp, proto, 0, 0));
bp = m_pullup(proto_Prepend(bp, PROTO_LQR, 0, 0));
bp = proto_Prepend(bp, *proto, l->lcp.his_protocomp,
struct mbuf *proto_Prepend(struct mbuf *, u_short, unsigned, int);