Eclipse Mosquitto™ 1.6.12

Security:

- In some circumstances, Mosquitto could leak memory when handling PUBLISH

 messages. This is limited to incoming QoS 2 messages, and is related

 to the combination of the broker having persistence enabled, a clean

 session=false client, which was connected prior to the broker restarting,

 then has reconnected and has now sent messages at a sufficiently high rate

 that the incoming queue at the broker has filled up and hence messages are

 being dropped. This is more likely to have an effect where

 max_queued_messages is a small value. This has now been fixed. Closes #1793.



Broker:

- Build warning fixes when building with WITH_BRIDGE=no and WITH_TLS=no.



Clients:

- All clients exit with an error exit code on CONNACK failure. Closes #1778.

- Don't busy loop with `mosquitto_pub -l` on a slow connection.