webkitgtk: add darwin support

pkgs/development/libraries/pango/default.nix

@@ -2,6 +2,8 @@
 , fontconfig, freetype, libintlOrEmpty, gobjectIntrospection
 }:
 
+with stdenv.lib;
+
 let
   ver_maj = "1.38";
   ver_min = "1";
@@ -29,6 +31,8 @@ stdenv.mkDerivation rec {
   # .../bin/sh: line 5: 14823 Abort trap: 6 srcdir=. PANGO_RC_FILE=./pangorc ${dir}$tst
   # FAIL: testiter
 
+  configureFlags = optional stdenv.isDarwin "--without-x";
+
   postInstall = "rm -rf $out/share/gtk-doc";
 
   meta = with stdenv.lib; {