Utf8 data is variable-width, ideally we want to write characters at most
once, so insert directly into the QString buffer if inserting at the end
(by delegating to append(QUtf8SV)), and use an intermediate buffer to
hold the converted data before inserting anywhere else.
Task-number: QTBUG-108546
Change-Id: Iabfaeecaf34a1ba11946bd67951e69a45d954d6d
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>
5f73f48556