[gtk+] window: Use correct destroy notify for icon list

[Timm Bäder <baedert src gnome org>]

commit 7ee2ab32b89e34d312cb4138a2832522a28ce9f1
Author: Timm Bäder <mail baedert org>
Date:   Mon Oct 23 14:43:47 2017 +0200

    window: Use correct destroy notify for icon list
    
    The list contains cairo_surface_t instances now, not GdkPixbuf anymore.

 gtk/gtkwindow.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index d0d1e45..1e87600 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -4529,7 +4529,7 @@ gtk_window_realize_icon (GtkWindow *window)
 
   if (info->using_themed_icon) 
     {
-      g_list_free_full (icon_list, g_object_unref);
+      g_list_free_full (icon_list, (GDestroyNotify)cairo_surface_destroy);
     }
 }