Replace class operators operator==(), operator!=() of
QtPrivate::ResultIteratorBase to friend method comparesEqual() and
Q_DECLARE_EQUALITY_COMPARABLE macro.
Use QT_CORE_REMOVED_SINCE and removed_api.cpp to get rid of
current comparison methods and replace them with a friend.
Task-number: QTBUG-120304
Change-Id: Ib9a50a400df86d1dc034d2a0cfee804109a2b93f
Reviewed-by: Ivan Solovev <ivan.solovev@qt.io>
ed71387d1c