No template constructor for QLatin1String

Qt 4.8 has a QLatin1Literal class with a template constructor

template<int N> QLatin1Literal(const char(&str)[N])

In Qt 5 QLatin1Literal is typedefed to QLatin1String, which has not such a constructor. QSting on the other hand has such a constructor, which was missing in Qt 4.8

If you now migrate QLatin1Literal optimized QT 4.8 code to Qt 5. The use of
QLatin1Literal becomes an de-optimizer.