CBD-1425:  no longer using BLD_DIR

Change-Id: I36965c3904d5deb4a239ea477fe5d88a6a2978ac
Reviewed-on: http://review.couchbase.org/40435
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>