QCollator can't sort according to "C" and "POSIX" locale definitions when Qt is compiled with ICU

#include <QCoreApplication>
#include <QDebug>
#include <QString>
#include <QCollator>
#include <QStringList>
#include <algorithm>
#include <locale>

int main(int argc, char** argv)
{
	QCoreApplication app(argc, argv);

	QStringList src;
	src << QLatin1String("Aaa");
	src << QLatin1String("AAa");
	src << QLatin1String("aba");
	src << QLatin1String("Bbb");
	src << QLatin1String("bab");

	QCollator collator;

	std::sort(src.begin(), src.end(), collator);
	qDebug() << "qcollator default :" << src;

	collator.setCaseSensitivity(Qt::CaseSensitive);
	std::sort(src.begin(), src.end(), collator);
	qDebug() << "qcollator force cs:" << src;

	collator.setCaseSensitivity(Qt::CaseInsensitive);
	std::sort(src.begin(), src.end(), collator);
	qDebug() << "qcollator force ci:" << src;

	struct Compare {
		bool operator()(const QString& left, const QString& right) {
			return std::locale("")(left.toStdString(), right.toStdString());
		}
	};

	std::sort(src.begin(), src.end(), Compare());;
	qDebug() << "std::locale       :" << src;

    return 0;
}