Locate the v8ver.cc in a better way

Change-Id: I92f847fba64b4a48535b4eef1d6c63d1f335a5ac
Reviewed-on: http://review.couchbase.org/32866
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>