$NetBSD: patch-configure,v 1.1 2012/08/08 00:13:54 marino Exp $

--- configure.orig	2012-05-01 20:48:03.000000000 +0000
+++ configure
@@ -16472,6 +16472,8 @@ main ()
 {
 #if (defined(__FreeBSD__) && ((__FreeBSD_version >= 500022 && __FreeBSD_version < 700000) || (__FreeBSD_version < 500000 && __FreeBSD_version >= 440000))) || (defined(__NetBSD__) && defined(__NetBSD_Version__) && __NetBSD_Version__ >= 106010000)
   return (0);
+#elif defined(__DragonFly__)
+  return (0);
 #else
   #error No support for BSD struct ip_mreq hack detected
 #endif
