kcms/region_language: use QLatin1String for "en_" text
We construct this string so that we can pass it to QString::startsWith(), which has a QLatin1String overload. Hence we can use a QLatin1String to save a tiny bit of memory here.
We construct this string so that we can pass it to QString::startsWith(), which has a QLatin1String overload. Hence we can use a QLatin1String to save a tiny bit of memory here.