[gtk+] gdkwindow-x11: Ensure that extended update counter is freed

[Matthias Clasen <matthiasc src gnome org>]

commit fa66b271f8c96d86bcb7eb7f315628ea3674aafd
Author: Ben Gamari <ben smart-cactus org>
Date:   Wed Jan 6 00:36:21 2016 +0100

    gdkwindow-x11: Ensure that extended update counter is freed
    
    I believe this lead to rampant leakage of SyncCounters by
    gnome-terminal.
    
    https://bugzilla.gnome.org/show_bug.cgi?id=760188

 gdk/x11/gdkwindow-x11.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)
---
diff --git a/gdk/x11/gdkwindow-x11.c b/gdk/x11/gdkwindow-x11.c
index 157ec3a..9f189ad 100644
--- a/gdk/x11/gdkwindow-x11.c
+++ b/gdk/x11/gdkwindow-x11.c
@@ -1297,7 +1297,10 @@ gdk_toplevel_x11_free_contents (GdkDisplay *display,
     {
       XSyncDestroyCounter (GDK_DISPLAY_XDISPLAY (display), 
                           toplevel->update_counter);
+      XSyncDestroyCounter (GDK_DISPLAY_XDISPLAY (display),
+                           toplevel->extended_update_counter);
       toplevel->update_counter = None;
+      toplevel->extended_update_counter = None;
 
       toplevel->current_counter_value = 0;
     }