win32: Ensure we always send a configure event when changing size/pos

There are some cases where we don't get a WINDOWPOSCHANGE such that
we generate a configure event, even if we called gdk_window_move_resize()
or similar. For instance:
* The window is fullscreen
* The window is maximized
* The specified pos/size is the same as the current one

However, as per X11 ConfigureNotify semantics we *always* want one, or
we could run into issue like e.g. bug #537296 where we're waiting for
the CONFIGURE to call gdk_window_thaw_toplevel_updates_libgtk_only().

gdk/win32/gdkprivate-win32.h

@@ -496,6 +496,7 @@ GdkAtom _gdk_win32_display_manager_atom_intern (GdkDisplayManager *manager,
 gchar *_gdk_win32_display_manager_get_atom_name (GdkDisplayManager *manager, 
 					         GdkAtom            atom);
 void _gdk_win32_append_event (GdkEvent *event);
+void _gdk_win32_emit_configure_event (GdkWindow *window);
 
 /* Initialization */
 void _gdk_win32_windowing_init (void);