wdx_stack_dstroy函数中免用脆弱点
https://access.redhat.com/errata/RHSA-2018:1296
https://bugs.php.net/bug.php?id=72860
https://github.com/php/php-src/commit/b88393f08a558eec14964a55d3c680fe67407712?w=1
https://security.gentoo.org/glsa/201611-22
//www.yyueer.com/security/tns-2016-19
http://www.openwall.com/lists/oss-security/2016/09/15/10
http://www.php.net/ChangeLog-5.php