title: OCaml int to binary string conversion
body: <p>What's the easiest way to convert an <code>Int32.t</code> to binary? For example:
  -1 -&gt; &quot;\255\255\255\255&quot; ?</p>
  <p>Edit:
  To use extlib, install it with yum and in the toplevel:</p>
  <pre><code>#use &quot;topfind&quot;;;
  #require &quot;extlib&quot;;;
  </code></pre>