[gimp] app: remove forgotten prototype from gui.c

[Michael Natterer <mitch src gnome org>]

commit 149e4af1709001bdf39cf4a69e09cb066c99adc1
Author: Michael Natterer <mitch gimp org>
Date:   Fri Jul 13 15:28:25 2018 +0200

    app: remove forgotten prototype from gui.c

 app/gui/gui.c | 3 ---
 1 file changed, 3 deletions(-)
---
diff --git a/app/gui/gui.c b/app/gui/gui.c
index d2b12a7b62..7897c2beb2 100644
--- a/app/gui/gui.c
+++ b/app/gui/gui.c
@@ -119,9 +119,6 @@ static gboolean   gui_exit_callback             (Gimp               *gimp,
 static gboolean   gui_exit_after_callback       (Gimp               *gimp,
                                                  gboolean            force);
 
-static void       gui_show_tooltips_notify      (GimpGuiConfig      *gui_config,
-                                                 GParamSpec         *pspec,
-                                                 Gimp               *gimp);
 static void       gui_show_help_button_notify   (GimpGuiConfig      *gui_config,
                                                  GParamSpec         *pspec,
                                                  Gimp               *gimp);