title: Undefined reference to process(std::__cxx11::basic_string ... ) when compiling affdex linux sample applications
body: <p>I encountered the following error when I tried to compile <a href="https://github.com/Affectiva/cpp-sdk-samples" rel="noreferrer">affdex sdk sample applications</a></p>
  
  <pre><code>Linking CXX executable video-demo
  CMakeFiles/video-demo.dir/video-demo.cpp.o: In function 'main':
  video-demo.cpp:(.text+0x11cb): undefined reference to 
  affdex::VideoDetector::process(std::__cxx11::basic_string&lt;char, std::char_traits&lt;char&gt;, std::allocator&lt;char&gt; &gt; const&amp;)
  collect2: error: ld returned 1 exit status
  </code></pre>
  
  <p>I'm using GCC 5.2.1</p>