QtIFW

Make sure we only calculate the components on actual change.

Change-Id: I5967f2fa2cba3e54519a4b8b5155b570d34d7a22
Reviewed-on: http://codereview.qt.nokia.com/3333
Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Niels Weber <niels.2.weber@nokia.com>
Reviewed-by: Tim Jenssen <tim.jenssen@nokia.com>