QLocale: create a static member function to return ISO 3166 country code for a give QLocale::Country value

Would be nice to have the feature mentioned in the summary. Currently I can only get a list of locales with QLocale::matchingLocales, and then split the result of QLocale::name() to get the country code. This method does not work for all countries. There are 29 countries, for I do not receive any locales.