title: How to get CMake variable of package in shellscript
body: <p>I want to find the <code>Qt5WaylandClient_PRIVATE_INCLUDE_DIRS</code> variable which is set by the Qt5WaylandClient package. How can I get it from the shell (dash)? Something like this:</p>
  
  <pre><code>cmake -find_package(Qt5WaylandClient) -get_variable Qt5WaylandClient_PRIVATE_INCLUDE_DIRS
  </code></pre>
  
  <p>or </p>
  
  <pre><code>cmake -file path/to/my/CMakeLists.txt -get_variable Qt5WaylandClient_PRIVATE_INCLUDE_DIRS
  </code></pre>