Reset ERL_LIBS before running RabbitMQ.

ERL_LIBS was inherited from the current environment, and it may
contain paths to older versions of amqp_client, which may not be
compatible with the current RabbitMQ management plugin.

As a result, RabbitMQ would not start when the management plugin was
enabled, with this error:

{could_not_start,amqp_client,
 {{supervisor_data,{invalid_strategy,simple_one_for_one_terminate}},
  {amqp_client,start,[normal,[]]}}}

net/rabbitmq/Makefile

@@ -3,6 +3,7 @@
 
 PORTNAME=	rabbitmq
 PORTVERSION=	3.2.2
+PORTREVISION=	1
 CATEGORIES=	net
 MASTER_SITES=	http://www.rabbitmq.com/releases/rabbitmq-server/v${PORTVERSION}/
 DISTNAME=	${PORTNAME}-server-${PORTVERSION}

net/rabbitmq/files/rabbitmq.in

@@ -36,6 +36,7 @@ extra_commands="rotate_logs status"
 rabbitmq_start()
 {
 	HOME=/var/db/rabbitmq
+	unset ERL_LIBS
 	su -m ${rabbitmq_user} \
 		-c "sh -c \"${rabbitmq_server} -detached\""
 # Grab pid (it appears that parsing the output of