[gtk] tool button: Use standard padding

[Matthias Clasen <matthiasc src gnome org>]

commit 4b5fee943eaa42a325c5c0ede6be59257ecf7b51
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue May 28 18:58:05 2019 -0400

    tool button: Use standard padding

 gtk/gtktoolbutton.h | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)
---
diff --git a/gtk/gtktoolbutton.h b/gtk/gtktoolbutton.h
index cbdae70ad6..5cefd1644b 100644
--- a/gtk/gtktoolbutton.h
+++ b/gtk/gtktoolbutton.h
@@ -68,11 +68,7 @@ struct _GtkToolButtonClass
 
   /*< private >*/
 
-  /* Padding for future expansion */
-  void (* _gtk_reserved1) (void);
-  void (* _gtk_reserved2) (void);
-  void (* _gtk_reserved3) (void);
-  void (* _gtk_reserved4) (void);
+  gpointer padding[8];
 };
 
 GDK_AVAILABLE_IN_ALL