Always compile but never run it unless UPDATEINFO_DISABLE
is being set to 'false' via qmake or environment.

Change-Id: Ie53fb2ea99bfebac1b6f416939554f25a5e481a7
Reviewed-on: http://codereview.qt-project.org/4483


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Eike Ziller <eike.ziller@nokia.com>
Reviewed-by: Tim Jenssen <tim.jenssen@nokia.com>