title: How to control subdirectory compiling order of cmake?
body: <p>This is my CMakeLists.txt:</p>
  
  <pre><code>ADD_SUBDIRECTORY(third)
  ADD_SUBDIRECTORY(utils)
  ADD_SUBDIRECTORY(rpc)
  </code></pre>
  
  <p>But the directory 'rpc' will be compiled before directory 'utils', actually the 'rpc' is depends on 'utils', so I will get a link error.</p>
  
  <p>How can I make the 'rpc' compiling after 'utils'?</p>
  
  <p>Thanks.</p>