Fix duplicate cfg definition in rr_client.

Closes #1453. Thanks to jveber.

ChangeLog.txt

@@ -12,6 +12,9 @@ Client library:
 - Fix publish properties not being passed to on_message_v5 callback for QoS 2
   messages. Closes #1432.
 
+Clients:
+- Fix duplicate cfg definition in rr_client. Closes #1453.
+
 
 1.6.7 - 20190925
 ================

client/rr_client.c

@@ -47,7 +47,8 @@ enum rr__state {
 
 static enum rr__state client_state = rr_s_new;
 
-struct mosq_config cfg;
+extern struct mosq_config cfg;
+
 bool process_messages = true;
 int msg_count = 0;
 struct mosquitto *mosq = NULL;