Have tree view process exposes after adjustments have been updated

This was removed long ago by the patch in bug 101235.  On a hindsight,
all other scrollable widgets are processing exposes at this point, which
completely makes sense to me, so I am putting it back.

gtk/gtktreeview.c

@@ -10531,6 +10531,9 @@ gtk_tree_view_adjustment_changed (GtkAdjustment *adjustment,
           if (!tree_view->priv->in_top_row_to_dy)
             gtk_tree_view_dy_to_top_row (tree_view);
 	}
+
+      gdk_window_process_updates (tree_view->priv->header_window, TRUE);
+      gdk_window_process_updates (tree_view->priv->bin_window, TRUE);
     }
 }