MB-11592 Fix upr snapshot marker flag values

EP-Engine has changed flag values for on-disk and in-memory
snapshot markers. Also a new flag "chk" has been added.

Change-Id: I8a262eb7856c97e11e95570fbdaef82f3f79054a
Reviewed-on: http://review.couchbase.org/39494
Reviewed-by: Michael Wiederhold <mike@couchbase.com>
Tested-by: Michael Wiederhold <mike@couchbase.com>