Fix little unregister buglet

git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@3540 65c4cc65-6c06-0410-ace0-fbb531ad65f3

channels/chan_zap.c

@@ -8474,6 +8474,8 @@ static int __unload_module(void)
 	ast_manager_unregister( "ZapDialOffhook" );
 	ast_manager_unregister( "ZapHangup" );
 	ast_manager_unregister( "ZapTransfer" );
+	ast_manager_unregister( "ZapDNDoff" );
+	ast_manager_unregister( "ZapDNDon" );
 	ast_unregister_application(app_callingpres);
 	ast_channel_unregister(typecompat);
 	ast_channel_unregister(type);