title: clinfo shows "Number of platforms 0"
body: <p>I'm developing on Centos 7.6 64bit and Nvidia graphic card.
  I've installed Nvidia driver and cuda driver.</p>
  
  <p>But, when I run "clinfo", it shows:</p>
  
  <pre><code>Number of platforms                               0
  </code></pre>
  
  <p>What should I check and how can I solve it?</p>