Add waiting_trans_ack also to fragmentation layer

Patch for support waiting_trans_ack may fail if there is synchronization
happening between delivery of fragmented message. In such situation,
fragmentation layer is waiting for message with correct number, but it
will never arrive.

Solution is to handle (callback) change of waiting_trans_ack and use
different queue.

Signed-off-by: Jan Friesse <jfriesse@redhat.com>
Reviewed-by: Fabio M. Di Nitto <fdinitto@redhat.com>