Try to make sure the config test script is installed.

Try to make sure the config test script is installed.

And try to fail a bit more gracefully if it isn't.

Change-Id: I62e01c0536aa0a032940d6a9a5ccf5edcfeef221
Reviewed-on: http://codereview.qt.nokia.com/2109
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Rohan McGovern <rohan.mcgovern@nokia.com>
Reviewed-by: Michael Goddard <michael.goddard@nokia.com>