title: PHP7.2 crash with php7.2-mbstring
body: <p>I  caught mistake with php vars</p>
  
  <pre><code>php_admin_value[mbstring.func_overload] = 2
  </code></pre>
  
  <p>But wihout this options its all right!
  But I am needing this option!!!</p>
  
  <pre><code>[01-Dec-2017 13:42:12] NOTICE: fpm is running, pid 10997
  [01-Dec-2017 13:42:12] NOTICE: ready to handle connections
  [01-Dec-2017 13:42:12] NOTICE: systemd monitor interval set to 10000ms
  [01-Dec-2017 13:43:25] WARNING: [pool www] child 10999 exited on signal 11 (SIGSEGV - core dumped) after 73.0072
  08 seconds from start
  [01-Dec-2017 13:43:25] NOTICE: [pool www] child 11470 started
  [01-Dec-2017 13:43:29] WARNING: [pool www] child 10998 exited on signal 11 (SIGSEGV - core dumped) after 76.4018
  86 seconds from start
  </code></pre>
  
  <p>php-mbstring version</p>
  
  <pre><code>Package: php7.2-mbstring
  Version: 7.2.0-1+ubuntu16.04.1+deb.sury.org+1
  </code></pre>
  
  <p>php version</p>
  
  <pre><code>PHP 7.2.0-1+ubuntu16.04.1+deb.sury.org+1 (cli) (built: Nov 30 2017     13:58:33) ( NTS )
  Copyright (c) 1997-2017 The PHP Group
  Zend Engine v3.2.0, Copyright (c) 1998-2017 Zend Technologies with Zend OPcache v7.2.0-1+ubuntu16.04.1+deb.sury.org+1, Copyright (c) 1999-2017, by Zend Technologie
  </code></pre>
  
  <p>My including extensions</p>
  
  <blockquote>
    <p>/etc/php/7.2/mods-available/mysqlnd.ini
    /etc/php/7.2/mods-available/opcache.ini
    /etc/php/7.2/mods-available/pdo.ini
    /etc/php/7.2/mods-available/xml.ini
    /etc/php/7.2/mods-available/calendar.ini
    /etc/php/7.2/mods-available/ctype.ini
    /etc/php/7.2/mods-available/curl.ini
    /etc/php/7.2/mods-available/dom.ini
    /etc/php/7.2/mods-available/exif.ini
    /etc/php/7.2/mods-available/fileinfo.ini
    /etc/php/7.2/mods-available/ftp.ini /etc/php/7.2/mods-available/gd.ini
    /etc/php/7.2/mods-available/gettext.ini
    /etc/php/7.2/mods-available/iconv.ini
    /etc/php/7.2/mods-available/igbinary.ini
    /etc/php/7.2/mods-available/imagick.ini
    /etc/php/7.2/mods-available/json.ini
    /etc/php/7.2/mods-available/ldap.ini
    /etc/php/7.2/mods-available/mbstring.ini
    /etc/php/7.2/mods-available/mysqli.ini
    /etc/php/7.2/mods-available/pdo_mysql.ini
    /etc/php/7.2/mods-available/phar.ini
    /etc/php/7.2/mods-available/posix.ini
    /etc/php/7.2/mods-available/readline.ini
    /etc/php/7.2/mods-available/redis.ini
    /etc/php/7.2/mods-available/shmop.ini
    /etc/php/7.2/mods-available/simplexml.ini
    /etc/php/7.2/mods-available/soap.ini
    /etc/php/7.2/mods-available/sockets.ini
    /etc/php/7.2/mods-available/sysvmsg.ini
    /etc/php/7.2/mods-available/sysvsem.ini
    /etc/php/7.2/mods-available/sysvshm.ini
    /etc/php/7.2/mods-available/tokenizer.ini
    /etc/php/7.2/mods-available/wddx.ini
    /etc/php/7.2/mods-available/xmlreader.ini
    /etc/php/7.2/mods-available/xmlwriter.ini
    /etc/php/7.2/mods-available/xsl.ini
    /etc/php/7.2/mods-available/zip.ini</p>
  </blockquote>
  
  <p>Please! Help me!</p>