title: Qt5 missing opengl identifier's
body: <p>i try to compile simple Qt application and port it to Qt5 
  in the pro file i included the opengl flag :</p>
  
  <pre><code>QT += opengl widgets 
  </code></pre>
  
  <p>also the opengl Qt5 path is included :</p>
  
  <pre><code>..\..\..\..\..\..\..\..\Qt\Qt5.0.1\5.0.1\msvc2010\include\QtOpenGL
  </code></pre>
  
  <p>but when i compile the app im getting those compilation errors</p>
  
  <pre><code>1&gt;qmpwidget.cpp(148): error C3861: 'glClearDepth': identifier not found
  1&gt;qmpwidget.cpp(159): error C3861: 'glLoadIdentity': identifier not found
  1&gt;qmpwidget.cpp(167): error C2065: 'GL_QUADS' : undeclared identifier
  1&gt;qmpwidget.cpp(167): error C3861: 'glBegin': identifier not found
  1&gt;qmpwidget.cpp(168): error C3861: 'glTexCoord2f': identifier not found
  1&gt;qmpwidget.cpp(168): error C3861: 'glVertex2f': identifier not found
  1&gt;qmpwidget.cpp(169): error C3861: 'glTexCoord2f': identifier not found
  1&gt;qmpwidget.cpp(169): error C3861: 'glVertex2f': identifier not found
  1&gt;qmpwidget.cpp(170): error C3861: 'glTexCoord2f': identifier not found
  1&gt;qmpwidget.cpp(170): error C3861: 'glVertex2f': identifier not found
  1&gt;qmpwidget.cpp(171): error C3861: 'glTexCoord2f': identifier not found
  1&gt;qmpwidget.cpp(171): error C3861: 'glVertex2f': identifier not found
  1&gt;qmpwidget.cpp(172): error C3861: 'glEnd': identifier not found
  </code></pre>
  
  <p>other opengl command do recognazied
  what im missing here ?</p>