There is the possibility that a stream is stopped and no data are read
from the audio source, e.g the fifo, anymore. The result is that iPaused is
true and nread is -1 when the timer expires.
For now, the halt flag is only sent to the receivers if nread is positive.
For notifying the receivers in case the stream is stopped and no data
are read from the source, lets send an empty audio message for
transmitting the halt flag.
Signed-off-by: Jörg Krause joerg.krause@embedded.rocks
