title: qmake set install directory
body: <p>I'm trying to build <a href="http://qwt.sourceforge.net/" rel="nofollow noreferrer">Qwt</a> to a custom location. The obvious thing to try is a <code>PREFIX</code> option, but it had no effect and the <code>make install</code> still failed:</p>
  
  <pre><code>$ qmake qwt.pro PREFIX='/my/path'
  $ make
  $ make install
  mkdir: cannot create directory `/usr/local/qwt-5.2.3': Permission denied
  </code></pre>
  
  <p>There seem to be numerous other questions and answers to this question, which also have no effect and fail:</p>
  
  <ul>
  <li><a href="https://stackoverflow.com/questions/14639459/how-to-change-qmake-prefix-location">How to change qmake PREFIX location</a>: <code>qmake -set prefix '/my/path'</code></li>
  <li><a href="https://stackoverflow.com/questions/6217093/how-can-the-install-path-be-set-for-a-qt-project">How can the install path be set for a qt project</a>: <code>make; INSTALL_ROOT=/my/path; make install</code></li>
  </ul>
  
  <p>Any other suggestions?</p>
  
  <hr>
  
  <p><em>QMake version 2.01a<br>
  Using Qt version 4.5.3 in /opt/Qt4/4.5.2/qtsdk-2009.04/qt/lib<br>
  RHEL 5.10</em></p>