title: CMAKE library not linking
body: <p>Why this code does not produce anything?</p>
  
  <pre><code>link_directories(${CMAKE_SOURCE_DIR}/libs/mylib1)
  message("DIR: ${LINK_DIRECTORIES}")
  </code></pre>
  
  <p>I have problem on Windows that though I do <code>link_directories()</code> there is NO <code>-L...</code> flag when linking. I do create target after <code>link_directories</code> command as documentation suggests.</p>