title: how to check QT_VERSION to include different header?
body: <p>Qt4 and Qt5 have different organization of header files. So I need to check the qt version to include different things, for example:</p>
  
  <pre><code>#if QT_VERSION &gt;= 0x050000
      #include &lt;QtMultimedia&gt;
  #endif
  </code></pre>
  
  <p>however, this seems does not work. The QT_VERSION has not been defined. How can I solve this problem?</p>