rabbitmq-run.mk: Fix stop-brokers with NODES > 1

The seq command should include a -1 increment to stop nodes in reverse
order.  Previously, as an example with NODES=2, will run `seq 2 1`
which produces no items to iterate, so the entire stop-node loop does
not execute and the brokers are left running.

Author: jeckersb

mk/rabbitmq-run.mk

@@ -341,7 +341,7 @@ start-brokers start-cluster:
 	done
 
 stop-brokers stop-cluster:
-	@for n in $$(seq $(NODES) 1); do \
+	@for n in $$(seq $(NODES) -1 1); do \
 		nodename="rabbit-$$n@$$(hostname -s)"; \
 		$(MAKE) stop-node \
 		  RABBITMQ_NODENAME="$$nodename"; \