added misc:is_timeout_exit

Change-Id: I0e7129607e37384f816408adbdb2cdbab702490d
Reviewed-on: http://review.couchbase.org/42211
Tested-by: Aliaksey Kandratsenka <alkondratenko@gmail.com>
Reviewed-by: Aliaksey Artamonau <aliaksiej.artamonau@gmail.com>