[ShellGtkEmbed] base this on ClutterX11TexturePixmap, not ClutterGLX

As of 1.4, ClutterGLXTexturePixmap is identical to
ClutterX11TexturePixmap (with the differences having been moved into
the cogl layer). So make ShellGtkEmbed use the (introspected) X11
version, which then allows us to make the instance and class structs
public as well.

https://bugzilla.gnome.org/show_bug.cgi?id=608869

src/shell-gtk-embed.h

@@ -2,7 +2,7 @@
 #ifndef __SHELL_GTK_EMBED_H__
 #define __SHELL_GTK_EMBED_H__
 
-#include <clutter/glx/clutter-glx.h>
+#include <clutter/x11/clutter-x11.h>
 
 #include "shell-embedded-window.h"
 
@@ -15,6 +15,19 @@
 
 typedef struct _ShellGtkEmbed        ShellGtkEmbed;
 typedef struct _ShellGtkEmbedClass   ShellGtkEmbedClass;
+typedef struct _ShellGtkEmbedPrivate ShellGtkEmbedPrivate;
+
+struct _ShellGtkEmbed
+{
+    ClutterX11TexturePixmap parent;
+
+    ShellGtkEmbedPrivate *priv;
+};
+
+struct _ShellGtkEmbedClass
+{
+    ClutterX11TexturePixmapClass parent_class;
+};
 
 GType shell_gtk_embed_get_type (void) G_GNUC_CONST;
 ClutterActor *shell_gtk_embed_new (ShellEmbeddedWindow *window);