rd_kafka_poll before rd_kafka_destroy

[takaomag]

Hi,

Thank you so much for your cool module!

I have one suggestion about ngx_http_kafka_exit_worker.
https://github.com/brg-liuwei/ngx_kafka_module/blob/master/ngx_http_kafka_module.c#L386

In my opinion, rd_kafka_poll should be done until rd_kafka_outq_len(main_conf->rk) > 0, in order to ensure kafka messages to be delivered before exit.

rd_kafka_poll(main_conf->rk, 0);

while (rd_kafka_outq_len(main_conf->rk) > 0) {
    rd_kafka_poll(main_conf->rk, 100);
}

// TODO: rd_kafka_topic_destroy(each loc conf rkt );
rd_kafka_destroy(main_conf->rk);

• C example code in librdkafka repository
  https://github.com/edenhill/librdkafka/blob/master/examples/rdkafka_example.c#L619

[brg-liuwei]

Great!

Would you please commit a pull request?

[takaomag]

Thanks and done the pull request.
#10