title: bintohex() and random_bytes() functions are undefined in PHP 5.6 on Linux
body: <p>I'm trying to call</p>
  
  <pre><code>echo bintohex(random_bytes(30));
  </code></pre>
  
  <p>But my logs show</p>
  
  <pre><code>PHP Fatal error:  Call to undefined function bintohex()
  </code></pre>
  
  <p>PHP 5.6.17<br>
  Apache 2.2.15<br>
  CentOS 6.7<br>
  Mcrypt 2.5.8 <em>(installed and verified on phpinfo() page)</em><br>
  extension=mcrypt.so <em>(present)</em></p>
  
  <p>Any ideas why I can't find bintohex() or random_bytes() functions?</p>