[MB-10648]: cmake change to resolve build issue.

Change-Id: Ibc7c4f75ef68dc28fbd2cdee9323d789b63a4b54
Reviewed-on: http://review.couchbase.org/34951
Reviewed-by: Eric Limare <eric.limare@couchbase.com>
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>