moc should use std::addressof for taking an address instead of operator&

In case a parameter is of type that overrides operator&, it causes problems for moc generated code which would take the result of operator&() instead of the object address. Using std::addressof() in those cases should work better.

For example:

class F : public QObject {
 Q_OBJECT
public:
 void* operator&() { return nullptr; }
signals:
 void something(F&);
};

Results in this, where it causes _a[1] to be nullptr as it calls F::operator&():

// SIGNAL 0
void F::something(F & _t1)
{
    void *_a[] = { nullptr, const_cast<void*>(reinterpret_cast<const void*>(&_t1)) };
    QMetaObject::activate(this, &staticMetaObject, 0, _a);
}