title: QMake generating weird paths in makefile
body: <p>I'm using Qt 5.1.1 and running qmake on windows. </p>
  
  <p>I run qmake with the following command:</p>
  
  <pre><code>qmake.exe -spec win32-msvc2012 -tp vc project.pro
  </code></pre>
  
  <p>Somehow in my makefile it generates some weird relative paths:</p>
  
  <pre><code>INCPATH = -I"..\..\..\qt\qwt-6.1.0\src"
  </code></pre>
  
  <p>for example.</p>
  
  <p>My includepaths in the .pro file are the following:</p>
  
  <pre><code>INCLUDEPATH += \
  $$PWD \
  $$QWTDIR \
  </code></pre>
  
  <p>what did I do wrong? (The compiler searches for ......\ which it isn't allowed to access for sure)</p>
  
  <p>qwtdir is defined as:</p>
  
  <pre><code>QWTDIR = C:/qt/qwt-6.1.0/src
  </code></pre>