rename the expressions of some gtk-related libraries

now the default (and usually only) version is called default

pkgs/development/libraries/gdk-pixbuf/default.nix

@@ -0,0 +1,31 @@
+{ stdenv, fetchurl, pkgconfig, glib, libtiff, libjpeg, libpng, libX11, xz
+, jasper }:
+
+stdenv.mkDerivation rec {
+  name = "gdk-pixbuf-2.26.5";
+
+  src = fetchurl {
+    url = "mirror://gnome/sources/gdk-pixbuf/2.26/${name}.tar.xz";
+    sha256 = "112w3xl16vam72d5mj1gvs1dgr0aipbxp0qq189mmadwcg8nysbp";
+  };
+
+  # !!! We might want to factor out the gdk-pixbuf-xlib subpackage.
+  buildInputs = [ libX11 ];
+
+  buildNativeInputs = [ pkgconfig ];
+
+  propagatedBuildInputs = [ glib libtiff libjpeg libpng jasper ];
+
+  configureFlags = "--with-libjasper --with-x11";
+
+  postInstall = "rm -rf $out/share/gtk-doc";
+
+  meta = {
+    description = "A library for image loading and manipulation";
+
+    homepage = http://library.gnome.org/devel/gdk-pixbuf/;
+
+    maintainers = [ stdenv.lib.maintainers.eelco ];
+    platforms = stdenv.lib.platforms.linux;
+  };
+}