Add a QnxBaseConfiguration class as base class for
the BlackBerryApiLevelConfiguration and the new
QnxConfiguarion classes.

The split of the BlackBerryApiLevelConfiguration logic
makes the code more flexible to add support for
the user's SDP/Qnx configurations.

Upcoming patches adding support for the SDP/Qnx configuration
will depend on this change.

Change-Id: I44258d9a9f0dc44bb196f4178974ad04d4caf70a
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>