avahi: fix build on darwin

pkgs/development/libraries/avahi/default.nix

@@ -1,5 +1,6 @@
 { fetchurl, stdenv, pkgconfig, libdaemon, dbus, perl, perlXMLParser
-, expat, gettext, intltool, glib, qt4 ? null, libiconvOrEmpty
+, expat, gettext, intltool, glib, libiconvOrEmpty
+, qt4 ? null
 , qt4Support ? false
 , withLibdnssdCompat ? false }:
 
@@ -25,23 +26,29 @@ stdenv.mkDerivation rec {
     [ "--disable-qt3" "--disable-gdbm" "--disable-mono"
       "--disable-gtk" "--disable-gtk3"
       "--${if qt4Support then "enable" else "disable"}-qt4"
-      "--disable-python"
-      "--with-distro=none" "--localstatedir=/var"
-    ] ++ stdenv.lib.optional withLibdnssdCompat "--enable-compat-libdns_sd";
-
-  meta = {
+      "--disable-python" "--localstatedir=/var" "--with-distro=none" ]
+    ++ stdenv.lib.optional withLibdnssdCompat "--enable-compat-libdns_sd"
+    # autoipd won't build on darwin
+    ++ stdenv.lib.optional stdenv.isDarwin "--disable-autoipd";
+
+  preBuild = stdenv.lib.optionalString stdenv.isDarwin ''
+    sed -i '20 i\
+    #define __APPLE_USE_RFC_2292' \
+    avahi-core/socket.c
+  '';
+
+  meta = with stdenv.lib; {
     description = "Avahi, an mDNS/DNS-SD implementation";
+    homepage    = http://avahi.org;
+    license     = licenses.lgpl2Plus;
+    platforms   = platforms.unix;
+    maintainers = with maintainers; [ lovek323 ludo ];
+
     longDescription = ''
       Avahi is a system which facilitates service discovery on a local
       network.  It is an implementation of the mDNS (for "Multicast
       DNS") and DNS-SD (for "DNS-Based Service Discovery")
       protocols.
     '';
-
-    homepage = http://avahi.org;
-    license = "LGPLv2+";
-
-    platforms = stdenv.lib.platforms.linux;  # arbitrary choice
-    maintainers = [ stdenv.lib.maintainers.ludo ];
   };
 }