title: Fixing "crc32 tool not found" on Ubuntu
body: <p>I'm trying to build <a href="https://github.com/spark/firmware" rel="noreferrer">spark/firmware</a> on Ubuntu, but when running <code>make</code> I only get the following error message</p>
  
  <pre><code>../build/common-tools.mk:26: *** "crc32 tool is not found".  Stop.
  </code></pre>
  
  <p>I tried using</p>
  
  <pre><code>apt-get install crc32
  </code></pre>
  
  <p>but there is no such package. How can I install the <code>crc32</code> tool?</p>