automagically grow value buffer if stat value is too long
automagically grow value buffer if stat value is too long

Change-Id: I1474ccff5407c153ebaa1ec399696e8ac7b478a0
Reviewed-on: http://review.membase.org/4466
Reviewed-by: Steve Yen <ef850f73f7832052d3c6d9b5ddd3a1716d9a57f1@gmail.com>
Tested-by: Aliaksey Kandratsenka <340b8e09ca65cd3fc686427fcfed17e87eaf61e2@gmail.com>

zbase/moxi,zbase/moxi,membase/moxi,zbase/moxi,zbase/moxi,membase/moxi,couchbase/moxi,membase/moxi,couchbase/moxi,couchbase/moxi,couchbase/moxi,membase/moxi,couchbase/moxi,membase/moxi,couchbase/moxi,membase/moxi,zbase/moxi