Log Message:
memcached: Update to 1.6.9

This change has a few useful new features, along with a lot of bugfixes and some \ 
internal code reorganization for future projects. We have been questing to \ 
improve test quality and stamp down bugs that came in over the 1.6 series.

As usual many thanks to the numerous contributors who sent in patches or helped \ 
test this release!

Fixes

    crawler: remove bad mutex unlock during error
    idle_timeout: avoid long hangs during shutdown
    extstore: use fcntl locking on disk file
    portability fix for getsubopt
    illumos build fixes + require libevent2
    core: generalize extstore's defered IO queue
    fix connection limit tests
    logger: fix spurious watcher hangups
    watcher.t: reduce flakiness
    Extend test CA validity to 500 years
    adjust "t/idle-timeout.t" be more forgiving

New Features

    arm64: Re-add arm crc32c hw acceleration for extstore
    restart mode: expose memory_file path in stats settings
    'shutdown graceful' command for raising SIGUSR1
    Introduce NAPI ID based worker thread selection (see doc/napi_ids.txt)
    item crawler hash table walk mode