title: Unknown module(s) in QT: core gui while using pre compiled build for mingw-64
body: <p>I have downloaded Qt5.6 pre compiled for mingw-64 , i have create qt.conf file also to change predefined path, when using qmake its giving error as shown.
  same command i am using</p>
  
  <p>D:\PROGRAMS\mingwtest\mingw_test>qmake -spec D:\QT\Qt-5.6\mkspecs\win32-g++ -o M
  akefile mingw_test.pro
   Project ERROR: Unknown module(s) in QT: core gui</p>