Previously it handled Latin-1, which made it incompatible with UTF-8,
which is now our preferred 8-bit encoding. For Qt6 it is limited to
ASCII. Adjusted tests to match. QLatin1String::compare() turned out
to be relying on qstrnicmp()'s Latin-1 handling.
Removed some spurious Q_UNLIKELY()s and tidied up code a little in the
process.
[ChangeLog][QtCore][Important Behavior Changes] Encoding-dependent
features of QByteArrray are now limited to ASCII, where previously
they worked for the whole of Latin-1. This affects case-insensitive
comparison, notably including qstricmp() and qstrnicmp(), and
case-transforming functions.
Fixes: QTBUG-84323
Change-Id: I2925d9908f8654599195a2860847b17083911b41
Reviewed-by: Lars Knoll <lars.knoll@qt.io>
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
9dd8e655cd