BD-1246:  add support for 2.5.1 builds

Change-Id: I398fbde4515656998d01042522d4c6937b04fd0f
Reviewed-on: http://review.couchbase.org/33450
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>