Add missing header

Author: reeze

msgpack-variant.h

@@ -1,3 +1,18 @@
+/*
+   +----------------------------------------------------------------------+
+   | HipHop for PHP                                                       |
+   +----------------------------------------------------------------------+
+   | Copyright (c) 2014-2014 Baidu, Inc.                                  |
+   +----------------------------------------------------------------------+
+   | This source file is subject to version 3.01 of the PHP license,      |
+   | that is bundled with this package in the file LICENSE, and is        |
+   | available through the world-wide-web at the following url:           |
+   | http://www.php.net/license/3_01.txt                                  |
+   | If you did not receive a copy of the PHP license and are unable to   |
+   | obtain it through the world-wide-web, please send a note to          |
+   | [email protected] so we can mail you a copy immediately.               |
+   +----------------------------------------------------------------------+
+*/
 
 // HHVM Variant to msgpack implementation