Adapt to connection-related changes in qtbase

Adapt to connection-related changes in qtbase

The QQmlData hooks signalEmitted() and receivers() now receive the
index in the signal index range (i.e., excluding non-signal methods).
This was done to avoid Q(Meta)Object having to compute the class's
method offset; the signal offset should be sufficient for everyone.

This required adapting QQmlNotifier, QQmlBoundSignal,
QQmlPropertyCache and friends to use the signal index range whenever
a property's notify signal is involved in the internal connection
lists and property captures.

Using the signal index range also reduces the memory used for
NotifyList::notifies, since useless entries for non-signal methods
will no longer be created.

Change-Id: I62872fbea5a1f829b8b03bae3fc1e6acd84cf886
Reviewed-by: Aaron Kennedy <aaron.kennedy@nokia.com>