Add the projects in cmake as part of make clean

Change-Id: Ib286ff3c1f7b445ca9660c5f6246c34a15a7962d
Reviewed-on: http://review.couchbase.org/30680
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>