server: be locally vocal about communication issues

server: be locally vocal about communication issues

If we fail the CRC check or if we have a mismatched client/server,
then we can't reliably transmit anything across the wire. For that
case, in addition to attempting to relay this information across
the wire, also print a local warning.

This fixes a case where we silently exit when the client/server
versions aren't properly matched.

Fixes: https://github.com/axboe/fio/issues/620
Signed-off-by: Jens Axboe <axboe@kernel.dk>