As more and more progress bars might be present for different
purposes and we are not able to easily distinguish them
we need to use a more reliable way to wait for the end of
parsing a project.
Add a respective function and use the new approach where
this appears to be appropriate or necessary.
Change-Id: I20e2b9b0efd4785f8f0b1ddbc8496be111628669
Reviewed-by: Robert Loehning <robert.loehning@qt.io>