The base environment depends on *all* library pro files.
Do emit baseEnvironmentChanged accordingly.

Change-Id: Ia24f3d65492fbe7d2bb4f9fa9e46202ae1764213
Reviewed-on: http://codereview.qt-project.org/5991


Reviewed-by: Qt Sanity Bot <qt_sanity_bot@ovi.com>
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@nokia.com>