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

Change-Id: I9feda82beff4e930e18d6127f538622225b86d8f
Reviewed-on: http://review.couchbase.org/42373
Reviewed-by: Chiyoung Seo <chiyoung@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>