instead of trying to reverse-engineer it from the final target including
extension and possible bundle path, construct the basename explicitly.
this avoids that we mangle the filename if the actual target contains a
period for some reason.
Task-number: QTBUG-70097
Change-Id: I0bae9f010ab82e258680830250f8e28656f09d67
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>