title: Call to undefined function hash_equals() in Facebook/Helpers/FacebookRedirectLoginHelper.php
body: <p>I'm trying to get the basic info from the facebook user. I'm following official docs. I don't know how to get rid of this error.</p>
  
  <pre><code>session_start();
  require_once 'Facebook/autoload.php';
  $fb = new Facebook\Facebook([
    'app_id' =&gt; 'XXXXX', // Replace {app-id} with your app id
    'app_secret' =&gt; 'xxxxxxxxxx',
    'default_graph_version' =&gt; 'v2.2',
    ]);
  
  $helper = $fb-&gt;getRedirectLoginHelper();
  
  //Get the Access Token
  
  try {
          //access token for the account
          $access_token=$helper-&gt;getAccessToken();
  
  } catch (Facebook\Exceptions\FacebookResponseException $e) {
          echo 'Graph returned an erorr'. $e-&gt;getMessage();
          exit;
  }catch(Facebook\Exceptions\FacebookSDKException $e){
          echo 'Graph returned an erorr'. $e-&gt;getMessage();
          exit;
  }
  
  echo '&lt;h3&gt;Access Token&lt;/h3&gt;';
  var_dump($accessToken-&gt;getValue());
  
  
  $loginUrl = $helper-&gt;getLoginUrl('https://startup-sarathjasrin.c9users.io/login/');
  
  echo '&lt;a href="' . htmlspecialchars($loginUrl) . '"&gt;Log in with Facebook!&lt;/a&gt;';
  </code></pre>
  
  <p>I'm using latest facebook-php-sdk-v5.</p>