title: fatal error: 'QTKit/QTKit.h' file not found when I build OpenCV on mac
body: <p>I have followed this <a href="http://www.pyimagesearch.com/2015/06/15/install-opencv-3-0-and-python-2-7-on-osx/" rel="noreferrer">http://www.pyimagesearch.com/2015/06/15/install-opencv-3-0-and-python-2-7-on-osx/</a> to install OpenCV on my mac.
  When I do this step :
      $ make -j4
  a problem happened:</p>
  
  <pre><code>fatal error: 
        'QTKit/QTKit.h' file not found
  #import &lt;QTKit/QTKit.h&gt;
          ^ 1 error generated. make[2]: *** [modules/videoio/CMakeFiles/opencv_videoio.dir/src/cap_qtkit.mm.o]
  Error 1 make[1]: ***
  [modules/videoio/CMakeFiles/opencv_videoio.dir/all] Error 2 make: ***
  [all] Error 2
  </code></pre>