[gtk+] Plug another memory leak

[Matthias Clasen <matthiasc src gnome org>]

commit 3f1dc87188eb2e5156930494d8d6f415655b2f19
Author: Matthias Clasen <mclasen redhat com>
Date:   Tue Oct 28 16:07:25 2014 -0400

    Plug another memory leak
    
    Also found by valgrind.

 gdk/gdkwindow.c |    1 +
 1 files changed, 1 insertions(+), 0 deletions(-)
---
diff --git a/gdk/gdkwindow.c b/gdk/gdkwindow.c
index a4e2bbb..3bef1da 100644
--- a/gdk/gdkwindow.c
+++ b/gdk/gdkwindow.c
@@ -3010,6 +3010,7 @@ gdk_window_mark_paint_from_clip (GdkWindow          *window,
       cairo_region_subtract (impl_window->current_paint.flushed_region, clip_region);
       cairo_region_union (impl_window->current_paint.need_blend_region, clip_region);
     }
+  cairo_region_destroy (clip_region);
 
   /* Clear the area on the double buffer surface to transparent so we
      can start drawing from scratch the area "above" the flushed