title: std type_traits conflict with Qt type_traits
body: <p>I have Qt 5.8 installed and i get this error.
  I also have CONFIG  += c++14 in my pro file and i also tried with c++11.</p>
  
  <pre><code>/usr/include/x86_64-linux-gnu/qt5/QtCore/qtimer.h:106: error: ‘is_same’ is not a member of ‘QtPrivate’!QtPrivate::is_same&lt;const 
  </code></pre>
  
  <p>also</p>
  
  <pre><code>/usr/include/c++/5/type_traits:958: note:   ‘std::is_same’
       struct is_same;
  </code></pre>