Add a 'd' to debug builds to allow both release and debug builds
to be used.
- Add .def-files for Debug
- Build all libraries debug/release
- Add description to README.qt
- Differentiate debug/release in qmake.conf.
Task-number: QTBUG-28196
Change-Id: Ib3081004a6ed2ad71d353244154684d2e0ebbc86
Reviewed-by: Andy Shaw <andy.shaw@digia.com>