CBQE-1128: fix for undefined qtime var

when exception is thrown during query request we cannot return qtime because it is undefined

Change-Id: I07399482826e194678b806780f8036a473f0718c
Reviewed-on: http://review.couchbase.org/25166
Tested-by: buildbot <build@couchbase.com>
Reviewed-by: Tommie McAfee <tommie@couchbase.com>