How can I solve "laravel/horizon v1.1.0 requires ext-pcntl * -> the requested PHP extension pcntl is missing from your system"? : <p>When I run <code>composer install</code> on command promp, there exist error like this : </p>

<pre><code>  Problem 1
    - Installation request for laravel/horizon v1.1.0 -&gt; satisfiable by laravel/horizon[v1.1.0].
    - laravel/horizon v1.1.0 requires ext-pcntl * -&gt; the requested PHP extension pcntl is missing from your system.

  To enable extensions, verify that they are enabled in your .ini files:
    - C:\xampp-7.1\php\php.ini
  You can also run `php --ini` inside terminal to see which files are used by PHP in CLI mode.
</code></pre>

<p>How can I solve this error?</p>
