Needed for proper building with ipv6 disabled
http://marc.info/?l=tcpdump-workers&m=122606195828825&w=2
--- a/print-enc.c	2008-11-04 16:24:30 +0000
+++ b/print-enc.c	2008-11-04 16:45:04 +0000
@@ -77,9 +77,11 @@
 	case AF_INET:
 		ip_print(gndo, p, length);
 		break;
+#ifdef INET6
 	case AF_INET6:
 		ip6_print(p, length);
 		break;
+#endif /*INET6*/
 	}
 
 out: