[libchamplain] launcher-gtk: Add missing NULL at the end of gdk_pixbuf_save_to_stream()

[Jiří Techet <jiritechet src gnome org>]

commit d682bea291049422427fc8fb961d6b721787bd94
Author: Jiří Techet <techet gmail com>
Date:   Thu Sep 29 23:34:07 2016 +0200

    launcher-gtk: Add missing NULL at the end of gdk_pixbuf_save_to_stream()
    
    gdk_pixbuf_save_to_stream() is a vararg function whose vararg parameters
    have to be NULL-terminated.

 demos/launcher-gtk.c |    2 +-
 1 files changed, 1 insertions(+), 1 deletions(-)
---
diff --git a/demos/launcher-gtk.c b/demos/launcher-gtk.c
index 70975b4..450f999 100644
--- a/demos/launcher-gtk.c
+++ b/demos/launcher-gtk.c
@@ -253,7 +253,7 @@ export_png (GtkButton     *button,
       return;
     }
 
-  gdk_pixbuf_save_to_stream (pixbuf, G_OUTPUT_STREAM (os), "png", NULL, NULL);
+  gdk_pixbuf_save_to_stream (pixbuf, G_OUTPUT_STREAM (os), "png", NULL, NULL, NULL);
   g_output_stream_close (G_OUTPUT_STREAM (os), NULL, NULL);
 }