rem: if (len < MHLEN)
add: if (len < (int) MHLEN)
context: struct mbuf *m_prepend(struct mbuf *m, int len){	struct mbuf *mnew;	if (M_LEADINGSPACE(m) >= len) {		m->m_data -= len;		m->m_len += len;	} else {		MGET(mnew, m->m_type);		if (!mnew) {			/* free chain */			return NULL;		}		if (m->m_flags & M_PKTHDR)			M_MOVE_PKTHDR(mnew, m);		mnew->m_next = m;		m = mnew;		if (len < MHLEN)			MH_ALIGN(m, len);		m->m_len = len;	}	if (m && m->m_flags & M_PKTHDR)		m->m_pkthdr.len += len;	return m;}