Split some GTK/X11-related packages

The closure of the Pan newsreader is now down from 344 MiB to 195 MiB.

pkgs/development/libraries/gdk-pixbuf/2.24.x.nix

@@ -9,6 +9,10 @@ stdenv.mkDerivation {
     sha256 = "1qdywh1r75lalb7z6s9pm6pmqx82chrrxqb8cdqi629nvc03yyns";
   };
 
+  outputs = [ "dev" "out" "bin" "doc" ];
+
+  enableParallelBuilding = true;
+
   # !!! We might want to factor out the gdk-pixbuf-xlib subpackage.
   buildInputs = [ libX11 ];
 
@@ -18,8 +22,6 @@ stdenv.mkDerivation {
 
   configureFlags = "--with-libjasper --with-x11";
 
-  postInstall = "rm -rf $out/share/gtk-doc";
-
   meta = {
     description = "A library for image loading and manipulation";