title: Travis build gcc fails include plugin header
body: <p>I am trying to build a project with Travis. The Makefile has the following include:</p>
  
  <pre><code>-I$(shell $(TARGET_CC) -print-file-name=plugin)/include
  </code></pre>
  
  <p>Which was supposed to give the <code>plugin</code> directory for <code>gcc</code>.</p>
  
  <pre><code>${CC} -print-file-name=plugin
  plugin
  ${CC} -print-file-name=plugin/include/gcc-plugin.h
  plugin/include/gcc-plugin.h
  ${CC} -print-file-name=gcc-plugin.h
  gcc-plugin.h
  </code></pre>
  
  <p>Build fails with error:</p>
  
  <pre><code>fatal error: gcc-plugin.h: No such file or directory
  </code></pre>
  
  <p>This header is supposed to be located in the <code>gcc</code> <code>plugin</code> library. What could go wrong with it?</p>
  
  <p>Project is open sourced at <a href="https://github.com/aoboturov/lua-hdf5" rel="nofollow">https://github.com/aoboturov/lua-hdf5</a></p>