Qmake does not find build_config

When trying to run qmake from creator or command line, I get the following error message

C:\qt\Qt5.0.0-rc1\5.0.0-rc1\Src\qtbase\examples\embedded\raycasting>qmake
C:/qt/Qt5.0.0-rc1/5.0.0-rc1/Src/qtbase/.qmake.conf:1: Cannot find feature qt_build_config
Project ERROR: Cannot load qmodule.pri!
Error processing project file: C:\qt\Qt5.0.0-rc1\5.0.0-rc1\Src\qtbase\examples\embedded\raycasting\raycasting.pro

This means that I cannot build any qt-project with this package.