Fix ARG_INFO for levenshtein

This can work with 2 parameters (require)

refs http://php.net/manual/ru/function.levenshtein.php
refs zephir-lang/zephir#753

Author: ovr

ext/standard/basic_functions.c

@@ -1574,12 +1574,14 @@ ZEND_BEGIN_ARG_INFO(arginfo_iptcparse, 0)
 	ZEND_ARG_INFO(0, iptcdata)
 ZEND_END_ARG_INFO()
 /* }}} */
+
 /* {{{ lcg.c */
 ZEND_BEGIN_ARG_INFO(arginfo_lcg_value, 0)
 ZEND_END_ARG_INFO()
 /* }}} */
+
 /* {{{ levenshtein.c */
-ZEND_BEGIN_ARG_INFO(arginfo_levenshtein, 0)
+ZEND_BEGIN_ARG_INFO_EX(arginfo_levenshtein, 0, 0, 2)
 	ZEND_ARG_INFO(0, str1)
 	ZEND_ARG_INFO(0, str2)
 	ZEND_ARG_INFO(0, cost_ins)