Fix out of source build

Change-Id: I8dfa068b018f26974da6bce814f7759f8c2ae01d
Reviewed-on: http://review.couchbase.org/35371
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>