[gtk] window: Remove default_icon_serial

[Matthias Clasen <matthiasc src gnome org>]

commit b215384064f76a7b2d36620c677084240defe40d
Author: Timm Bäder <mail baedert org>
Date:   Sun Dec 30 06:54:57 2018 +0100

    window: Remove default_icon_serial
    
    Now unused.

 gtk/gtkwindow.c | 5 -----
 1 file changed, 5 deletions(-)
---
diff --git a/gtk/gtkwindow.c b/gtk/gtkwindow.c
index bd217ab9c9..d52a087d92 100644
--- a/gtk/gtkwindow.c
+++ b/gtk/gtkwindow.c
@@ -523,7 +523,6 @@ static void gtk_window_state_flags_changed (GtkWidget     *widget,
 static GListStore  *toplevel_list = NULL;
 static guint        window_signals[LAST_SIGNAL] = { 0 };
 static gchar       *default_icon_name = NULL;
-static guint        default_icon_serial = 0;
 static gboolean     disable_startup_notification = FALSE;
 
 static GQuark       quark_gtk_window_key_hash = 0;
@@ -4775,10 +4774,6 @@ gtk_window_set_default_icon_name (const gchar *name)
   GList *tmp_list;
   GList *toplevels;
 
-  /* Update serial so we don't used cached pixmaps/masks
-   */
-  default_icon_serial++;
-
   g_free (default_icon_name);
   default_icon_name = g_strdup (name);