Update to FreeBSD head 2018-06-01

Git mirror commit fb63610a69b0eb7f69a201ba05c4c1a7a2739cf9.

Update #3472.

freebsd/contrib/libpcap/pcap-common.h

@@ -1,3 +1,25 @@
+/*
+ * Copyright (c) 1993, 1994, 1995, 1996, 1997
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that: (1) source code distributions
+ * retain the above copyright notice and this paragraph in its entirety, (2)
+ * distributions including binary code include the above copyright notice and
+ * this paragraph in its entirety in the documentation or other materials
+ * provided with the distribution, and (3) all advertising materials mentioning
+ * features or use of this software display the following acknowledgement:
+ * ``This product includes software developed by the University of California,
+ * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
+ * the University nor the names of its contributors may be used to endorse
+ * or promote products derived from this software without specific prior
+ * written permission.
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+ * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ *
+ * pcap-common.h - common code for pcap and pcapng files
+ */
 
 /*
  * We use the "receiver-makes-right" approach to byte order,
@@ -23,3 +45,5 @@ extern int linktype_to_dlt(int linktype);
 
 extern void swap_pseudo_headers(int linktype, struct pcap_pkthdr *hdr,
     u_char *data);
+
+extern u_int max_snaplen_for_dlt(int dlt);