title: Error:Could NOT find PkgConfig (missing: PKG_CONFIG_EXECUTABLE)
body: <p>I am using Point cloud library 1.5.1. When I run CMake 3.4.0-rc2 to build my project, it has error: </p>
  
  <pre><code>Could NOT find PkgConfig (missing: PKG_CONFIG_EXECUTABLE)
  </code></pre>
  
  <p>How do I fix this error?</p>