QGeoPositionInfo::timestamp() returns non UTC time on iOS

I tested on 5.11.3 but I see the problematic code is the same in 5.13 branch.

Techinfo:
Code in qgeopositioninfosource_cl.mm uses default constructor of QDateTime which has default Qt::LocalTime timespec default. Then it call setTime_t (followed by addMSecs).

https://github.com/qt/qtlocation/blob/5.13/src/plugins/position/corelocation/qgeopositioninfosource_cl.mm#L72

From the first look the best fix would be to call the following overload instead of setTime_t+addMSecs:

static QDateTime QDateTime::fromMSecsSinceEpoch(qint64 msecs, Qt::TimeSpec spec, int offsetFromUtc = 0);

And pass Qt::UTC timespec.