Maintenance release

Critical fixes

• q_concat: don't wakeup listeners if srcq is empty (fix by @orthrus in #1121): Fixes idle consumer CPU usage on Windows
• Prioritize commit_cb over messages on poll queue (closes #1088)
• Prioritize all relevant user-facing ops (callbacks) (#1088)
• Fix SaslHandshakeRequest timeout

Fixes

• Properly log SSL connection close (closes #1081)
• Don't log broker failures when an error_cb is registered (closes #1055)
• Fix use-after-free when log.queue and debug was used
• Log offset commit failures when there is no offset_commit_cb (closes #1043)
• Fix retrybuf memory leak on termination when broker is down
• Fix small memory leak in metadata_leader_query
• Use app_offset to calculate consumer_lag (closes #1112)
• Fix consumer_lag calculation (dont use cached hi_offset)
• C++: fix conf->get() allocation (closes #1118)
• Avoid use of partially destroyed topic object (#1125, fixed by @benli123)
• sasl win32: protection level and message size not sent (fixed by @zyzil )
• Properly auto-set metadata.max.age.ms when metadata.refresh.interval.ms is disabled (closes #1149)
• Fix memory alignment issues (#1150)
• consumer_example: fix crash on -X dump (closes #841)
• configure: auto add brew openssl pkg-config path
• producev() default partition should be UA, not 0 (#1153)

Enhancements

• Added global->topic config fallthru: Topic-level configuration properties can now be set on the global configuration object. The property will be applied on the default_topic_conf object (if no such object exists one is created automatically).
• Use SNI when connecting through SSL (by @vincentbernat )
• Windows performance improvements (use atomics instead of locks, avoid locking in some cases)
• Add lz4/lib sources for in-tree building when external lz4 is not available
• Add CRC checking support to consumer (#1056)
• Added op priority to queues (for #1088)
• Fail known unsupported requests locally (closes #1091)
• Improve reconnect delay handling (#1089)
• Improve OpenSSL config error propagation (#1119)
• C++: improved error reporting from Conf::set()
• Don't emit TIMED_OUT_QUEUE (revert)