syslog-ng: Enable systemd support

pkgs/tools/system/syslog-ng/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, eventlog, pkgconfig, glib, python }:
+{ stdenv, fetchurl, eventlog, pkgconfig, glib, python, systemd }:
 
 stdenv.mkDerivation {
   name = "syslog-ng-3.5.4.1";
@@ -8,8 +8,13 @@ stdenv.mkDerivation {
     sha256 = "0rkgrmnyx1x6m3jw5n49k7r1dcg79lxh900g74rgvd3j86g9dilj";
   };
 
-  buildInputs = [ eventlog pkgconfig glib python ];
-  configureFlags = "--enable-dynamic-linking";
+  buildInputs = [ eventlog pkgconfig glib python systemd ];
+
+  configureFlags = [
+    "--enable-dynamic-linking"
+    "--enable-systemd"
+    "--with-systemdsystemunitdir=$(out)/etc/systemd/system"
+  ];
 
   meta = {
     homepage = "http://www.balabit.com/network-security/syslog-ng/";