title: CMake doesn't know where is Qt4 qmake
body: <p>I am using Debian OS and I'm trying to point to cmake where is my Qt4.</p>
  
  <p>I try to build qjson library and with its CMakeLists.txt:
  <a href="http://pastebin.com/fKNp0Qgy">http://pastebin.com/fKNp0Qgy</a></p>
  
  <p>I get:</p>
  
  <pre><code>Qt5 not found, searching for Qt4
  qmake: could not exec '/usr/lib/x86_64-linux-gnu/qt4/bin/qmake': No such file or directory
  CMake Error at /usr/share/cmake-2.8/Modules/FindQt4.cmake:1386 (message):
    Found unsuitable Qt version "" from NOTFOUND, this code requires Qt 4.x
  Call Stack (most recent call first):
    CMakeLists.txt:55 (FIND_PACKAGE)
  
  
  -- Configuring incomplete, errors occurred!
  </code></pre>
  
  <p>I'm not familiar with CMake and Qt config, but I'm curious what setting force CMake FIND_PACKAGE to look into '/usr/lib/x86_64-linux-gnu/qt4/bin/qmake' for qmake.
  I have installed Qt 4.8.5 from source and I have Qt4 bin folder in completely different directory.</p>