LookupSucceededFilter is not thread safe

LookupSucceededFilter is used by server-side HA-JNDI to allow prompt return from group naming lookup RPCs once any server responds with a non-null, non-Exception value. However, concurrent access to its private boolean lookupSucceeded field is not controlled.

The effect of this bug is if two RPCs responses are received at the same time and one is null or an exception value (i.e. because of the not abnormal condition that the server that sent the response did not have the requested item in JNDI) it is possible that the RPC will not return promptly and instead will have to wait for all responses to be received.

The fix is to make the field volatile with an initial false value and only set to true when an acceptable result is received. The only state change is to true.