The previous code increases print_stall if a move is proactively
flushed due to buffer_time_low and a follow up move is ready to send
before the existing moves are fully retired. However, this would not
track the case where a move is proactively flushed and it takes an
extended amount of time to get sufficient moves to refill the queue.
Change the code so that print_stall increases anytime a new move is
queued after a proactive flush and there are existing moves not yet
fully retired.
Signed-off-by: Kevin O'Connor <kevin@koconnor.net>