MB-9864: Reset access log if less then header size

sometimes an incomplete write can result in access
log header being less than header size.
Do not throw Short Read exception, rather
simply recovery by removing and recreating the access log
Change-Id: I8d1250eb1e78dd71f57b7a30ed8d90defedde446
Reviewed-on: http://review.couchbase.org/31803
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Reviewed-by: Sundararaman Sridharan <sundar.sridharan@gmail.com>
Tested-by: Sundararaman Sridharan <sundar.sridharan@gmail.com>