patch 9.1.2011: crash when unreferencing gtk icon theme

Problem:  crash when unreferencing gtk icon theme
          (noamhalevy-wq, after v9.1.1583)
Solution: Remove the g_object_unref() call.

gtk_icon_theme_get_default() returns a singleton that should NOT be
unreferenced. From GTK documentation:

> A unique GtkIconTheme associated with the default screen. This icon
theme is associated with the screen and can be used as long as the
screen is open. Do not ref or unref it.

fixes: #18997

Signed-off-by: Christian Brabandt <cb@256bit.org>

Author: chrisbra

src/gui_gtk_x11.c

@@ -2750,9 +2750,7 @@ mainwin_realize(GtkWidget *widget UNUSED, gpointer data UNUSED)
 	icon_theme = gtk_icon_theme_get_default();
 
 	if (icon_theme && gtk_icon_theme_has_icon(icon_theme, "gvim"))
-	{
 	    gtk_window_set_icon_name(GTK_WINDOW(gui.mainwin), "gvim");
-	}
 	else
 	{
 	    /*
@@ -2770,7 +2768,6 @@ mainwin_realize(GtkWidget *widget UNUSED, gpointer data UNUSED)
 	    g_list_foreach(icons, (GFunc)(void *)&g_object_unref, NULL);
 	    g_list_free(icons);
 	}
-	g_object_unref(icon_theme);
     }
 
 #if !defined(USE_GNOME_SESSION)

src/version.c

@@ -734,6 +734,8 @@ static char *(features[]) =
 
 static int included_patches[] =
 {   /* Add new patch number below this line */
+/**/
+    2011,
 /**/
     2010,
 /**/