libdbusmenu: rename name to pname&version

pkgs/development/libraries/libdbusmenu/default.nix

···
 with lib;
 
 stdenv.mkDerivation rec {
-  name = let postfix = if gtkVersion == null then "glib" else "gtk${gtkVersion}";
-          in "libdbusmenu-${postfix}-${version}";
-  version = "${versionMajor}.${versionMinor}";
-  versionMajor = "16.04";
-  versionMinor = "0";
+  pname = "libdbusmenu-${if gtkVersion == null then "glib" else "gtk${gtkVersion}"}";
+  version = "16.04.0";
 
   src = fetchurl {
-    url = "${meta.homepage}/${versionMajor}/${version}/+download/libdbusmenu-${version}.tar.gz";
+    url = "https://launchpad.net/dbusmenu/${lib.versions.majorMinor version}/${version}/+download/libdbusmenu-${version}.tar.gz";
     sha256 = "12l7z8dhl917iy9h02sxmpclnhkdjryn08r8i4sr8l3lrlm4mk5r";
   };