When QCborValue referred to an empty array or map, toArray() and toMap()
would respectively return the default value instead of the empty object,
as expected.
Pick-to: 6.2 6.3
Change-Id: I5e52dc5b093c43a3b678fffd16b60456d0037ad7
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>