Enable cmake policy to fix @rpath
Enable cmake policy to fix @rpath

Change-Id: I33f4057206128c9cfd6150eee40e385c8e170926
Reviewed-on: http://review.couchbase.org/43403
Tested-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@gmail.com>
Reviewed-by: Dave Rigby <a09264da4832c7ff1d3bf1608a19f4b870f93750@couchbase.com>

couchbase/sigar,couchbase/sigar