New port: net/librdkafka

This is a port of librdkafka, a C library implementation
of the Apache Kafka protocol, containing both Producer and
Consumer support. It was designed with message delivery
reliability and high performance in mind, current figures
exceed 800000 msgs/second for the producer and 3 million
msgs/second for the consumer.

WWW: https://github.com/edenhill/librdkafka/

PR: 201521
Submitted by: Victor Yagofarov <xnasx@yandex.ru>