CBD-1425:  Don't make VLT_DIR or it will prevent git clone

Change-Id: I130a109edd0053bd3050bfe2fde9b8a887b3831d
Reviewed-on: http://review.couchbase.org/40393
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>