Qnx: Update bar-descriptor Qt environment if not matching the Qt bundle mode

If the user removes a bar-descriptor and adds it again, the Qt environments
need to be checked since the default values
are not necessary matching the Qt bundle mode
in the deployment settings.

Change-Id: I9f1e2699322d9868a29596da74e54d4323ea4e37
Reviewed-by: David Kaspar <dkaspar@blackberry.com>
Reviewed-by: Tobias Hunger <tobias.hunger@digia.com>