Fixup JSCBC-16 exit code ;)

Change-Id: I0df5dc58b5cedf360ae88f04a56124e6a1e316a8
Reviewed-on: http://review.couchbase.org/25755
Reviewed-by: Trond Norbye <trond.norbye@gmail.com>
Tested-by: Trond Norbye <trond.norbye@gmail.com>