title: In include file: 'math.h' file is not found. QT Creator
body: <p>I am using QT to display PCD file by VTK, I am facing the problem such like;
  In included file: 'math.h' file not found</p>
  <p>I have already checked the 'edit system environment variable', .pro file's INCLUDE file etc. etc.  that's fine.</p>
  <p>can anyone encounter such issue? please response, thanks indeed.</p>