omkafka: not detect all brokers failure.

[antry]

Expected behavior

When all kafka brokers down switch to failover due to suspend message.

Actual behavior

When all kafka brokers down and rsyslog restarted outgoing queue start increasing in omkafka
and no messages suspended and didn't switch to failover.
librdkafa 0.11.5 return no error in case if all brokers down.
starting with librdkafa 0.11.6 error code KAFKA_RESP_ERR__ALL_BROKERS_DOWN exists.
but it doesn't checked in current omkafka implementation.

Steps to reproduce the behavior

`if ( $syslogtag == 'nginx:') then {
action(
broker=["kafka-broker:9092"]
type="omkafka"
topic="topic"
template="json-nginx"
errorFile="/var/log/kafkaError.log"
Action.ResumeRetryCount="0"
Action.ReportSuspension="on"
confParam=["compression.codec=lz4","socket.timeout.ms=10","socket.keepalive.enable=true"]
)

action(
type="omfwd"
Target="logstash"
Port="5045"
Protocol="tcp"
action.resumeretrycount="-1"
template="json-nginx"
action.execOnlyWhenPreviousIsSuspended="on"
)
stop
}`

Environment

• rsyslog version: 8.1903.0
• platform: CentOS Linux release 7.6.1810 (Core)