MB-12328: Convert the dcp mutation flags field to network order

Change-Id: If5a06fb7b65bc0aacf44412169b8dd0b66f51ae1
Reviewed-on: http://review.couchbase.org/42080
Reviewed-by: Dave Rigby <daver@couchbase.com>
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>