The operator was not converted to using a new streaming version, so it
supported only 32-bit length.
Fix it and add a manual test for serialization/deserialization of
large c-style strings.
Amends fd48ce0b73c74dafd5db27bc1f2752ef665df7ef
Pick-to: 6.7
Change-Id: I83704edec021d400b992de810feba5da52d5ffe1
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>
0aaf7092cd