QMessageBox: use %ls and qUtf6Printable()

... instead of %s and qPrintable()

Less operations, less code expansion.

Amends 408fbd3f2d.

Pick-to: 6.6
Change-Id: I5a3d2e79623bd32c348a2d655e3a2c8d98eca1e3
Reviewed-by: Axel Spoerl <axel.spoerl@qt.io>

src/widgets/dialogs/qmessagebox.cpp

@@ -2860,7 +2860,7 @@ Q_WIDGETS_EXPORT void _q_requireVersion(int argc, char *argv[], QAnyStringView r
                                     .arg(qAppName(), required.toString(), current.toString());
     QMessageBox::critical(nullptr, QApplication::tr("Incompatible Qt Library Error"),
                           message, QMessageBox::Abort);
-    qFatal("%s", qPrintable(message));
+    qFatal("%ls", qUtf16Printable(message));
 }
 
 #if QT_DEPRECATED_SINCE(6,2)