NFSv4.1: Allow test_stateid to handle session errors without waiting

If the server crashes while we're testing stateids for validity, then
we want to initiate session recovery. Usually, we will be calling from
a state manager thread, though, so we don't really want to wait.

Signed-off-by: Trond Myklebust <trond.myklebust@primarydata.com>
Tested-by: Oleg Drokin <green@linuxhacker.ru>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>