Note that this really belongs in a unit test that builds the library
since it depends on a change to the library.

For this to work accurately a check in QSensorBackend::newReadingAvailable()
needs to be commented out while building the library. The check is:

    if (d->updatePolicy == QSensor::PolledUpdates)
        return; // We don't emit the signal if we're polling

With this check in place, the use of sensor.poll() to measure performance
does not work.