Extend the search for lua

Change-Id: Id1f14ae57a8a5d678079b0f2ed219bf52f98bcfb
Reviewed-on: http://review.couchbase.org/30295
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>