QSharedPointer: make QT_SHAREDPOINTER_TRACK_POINTERS work with QObjects

QSharedPointer: make QT_SHAREDPOINTER_TRACK_POINTERS work with QObjects

If setQObjectShared crashes because a QObject is tracked by two
different QSharedPointers, we lose the debug feature offered by #defining
QT_SHAREDPOINTER_TRACK_POINTERS, as the check done by this define
happens after the setQObjectShared call.

Therefore, move setQObjectShared after the internalSafetyCheckAdd call.

This is actually a noop change in 5.0, as setQObjectShared does nothing.
However it prevents a bug in case the Qt 4 behaviour is brought back
in some later version.

Change-Id: I71340d0f878828354537762d01c46d441efc918c
Reviewed-by: Thiago Macieira <thiago.macieira@intel.com>