distributor: fix flushing in flight packets

distributor: fix flushing in flight packets

rte_distributor_flush() is using total_outstanding()
function to calculate if it should still wait
for processing packets. However in burst mode
only backlog packets were counted.

This patch fixes that issue by counting also in flight
packets. There are also sum fixes to properly keep
count of in flight packets for each worker in bufs[].count.

Fixes: 775003ad2f96 ("distributor: add new burst-capable library")
Cc: stable@dpdk.org
Signed-off-by: Lukasz Wojciechowski <l.wojciechow@partner.samsung.com>
Acked-by: David Hunt <david.hunt@intel.com>