Like other backends we should increment the invalid character count
when we output a replacement character.
And we should also output the NULL character if requested!
The downside here is that convertFromUnicode doesn't even have the
ability to do so. So instead I added a comment explaining why it is not
handled there.
Task-number: QTBUG-118318
Pick-to: 6.7 6.6 6.5
Change-Id: I57ba631aa59454e77007ab353277b7e8c2b5526a
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>