have libQtDesigner load(qt_module_config) like all Qt libs

have libQtDesigner load(qt_module_config) like all Qt libs

load(qt_module_config) is the same as include(.../qbase.pri) before
and set up the library to match how Qt libraries are normally
configured. It's needed to pull in various thing like for example
CONFIG+=explicitlib, etc.

Also remove redundant QT += uilib-private

Change-Id: I273183ac95f19d3022e0427e64884f7634b01624
Reviewed-on: http://codereview.qt.nokia.com/1851
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Oswald Buddenhagen <oswald.buddenhagen@nokia.com>