Patch to use pledge on OpenBSD.

Index: lib/isc/netmgr/netmgr.c
--- lib/isc/netmgr/netmgr.c.orig
+++ lib/isc/netmgr/netmgr.c
@@ -3295,7 +3295,8 @@ isc__nm_socket_disable_pmtud(uv_os_sock_t fd, sa_famil
 	 * Disable the Path MTU Discovery on IP packets
 	 */
 	if (sa_family == AF_INET6) {
-#if defined(IPV6_DONTFRAG)
+/* disabled for pledge */
+#if !defined(__OpenBSD__) && defined(IPV6_DONTFRAG)
 		if (setsockopt_off(fd, IPPROTO_IPV6, IPV6_DONTFRAG) == -1) {
 			return (ISC_R_FAILURE);
 		} else {
@@ -3313,7 +3314,12 @@ isc__nm_socket_disable_pmtud(uv_os_sock_t fd, sa_famil
 		UNUSED(fd);
 #endif
 	} else if (sa_family == AF_INET) {
-#if defined(IP_DONTFRAG)
+/*
+   OpenBSD doesn't have this yet but if we do get it sometime,
+   it will probably need the same pledge handling as IPV6_DONTFRAG
+   above
+ */
+#if !defined(__OpenBSD__) && defined(IP_DONTFRAG)
 		if (setsockopt_off(fd, IPPROTO_IP, IP_DONTFRAG) == -1) {
 			return (ISC_R_FAILURE);
 		} else {
@@ -3343,7 +3349,11 @@ isc__nm_socket_v6only(uv_os_sock_t fd, sa_family_t sa_
 	 * Enable the IPv6-only option on IPv6 sockets
 	 */
 	if (sa_family == AF_INET6) {
-#if defined(IPV6_V6ONLY)
+/*
+ * pledge doesn't allow setting IPV6_V6ONLY, but that's ok,
+ * IPV6_V6ONLY is always enabled on OpenBSD
+ */
+#if !defined(__OpenBSD__) && defined(IPV6_V6ONLY)
 		if (setsockopt_on(fd, IPPROTO_IPV6, IPV6_V6ONLY) == -1) {
 			return (ISC_R_FAILURE);
 		} else {