MB-23863: Make DCP backfill read deleted documents

MB-23863: Make DCP backfill read deleted documents

recordDbDump is invoked for KVStore::scan (backfill) and was coded to
skip opening of the document if the docinfo says deleted.

This commit then removes the error case where
couchstore_open_doc_with_docinfo returns -5
(COUCHSTORE_ERROR_DOC_NOT_FOUND) as that just means the document has
no-value and we still need to continue to creating the Item.

Change-Id: I6e2e563ef68f9bc4404c5e59480f8c6fb2dd36e4
Reviewed-on: http://review.couchbase.org/76709
Tested-by: Build Bot <build@couchbase.com>
Reviewed-by: Dave Rigby <daver@couchbase.com>