shout2send: print actual username in debug log out

https://bugzilla.gnome.org/show_bug.cgi?id=782093
diff --git a/ext/shout2/gstshout2.c b/ext/shout2/gstshout2.c
index 64be764..3d3f652 100644
--- a/ext/shout2/gstshout2.c
+++ b/ext/shout2/gstshout2.c
@@ -502,7 +502,7 @@
     goto set_failed;
 
   cur_prop = "username";
-  GST_DEBUG_OBJECT (sink, "setting %s: %s", cur_prop, "source");
+  GST_DEBUG_OBJECT (sink, "setting %s: %s", cur_prop, sink->username);
   if (shout_set_user (sink->conn, sink->username) != SHOUTERR_SUCCESS)
     goto set_failed;