Truncate last unaligned bytes of access log

Truncating unaligned bytes of access log allows use of access log
even if last bytes are unaligned to blocksize.
Avoid throwing a ShortReadException which just disables the access log
Change-Id: I6e82fb0aa4b62e892e092c98654df71bee3f16d6
Reviewed-on: http://review.couchbase.org/36995
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: buildbot <build@couchbase.com>
Fix deadlock in checkpoint persistence command

We need to release the hpChkMutex before notifying memcached in
order to prevent a deadlock. The deadlock occurs when the flusher
trys to notify memcached of checkpoint persistence at the same
time a memcached worker thread is trying to add a new checkpoint
persistence request.

Change-Id: Ida313f5b39ef0e063dee9882410cd0a19ce55292
Reviewed-on: http://review.couchbase.org/41363
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>
Merge remote-tracking branch 'gerrit/2.5.0' into 3.0.1

Change-Id: I59c45877fc783e30c86dcfd7d303c731cde433fc