MB-7892: Use memset instead of bzero

memset is a standard function, whereas bzero is nonstandard
and possibly not found on all platforms (without special includes)

Change-Id: I13f40ecb443ed3316b6fe0a0cda6e77eb96099eb
Reviewed-on: http://review.couchbase.org/25088
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>