Update the event-loop for sync NFS commands to handle timeouts better.

Change the loop so poll will timeout after 100ms so that we get 100ms
granularity on the timer that drives the timeouts.

Secondly, stop treating poll returning 0 as an error as this will be normal
if an application use sync NOF commands set to >>100ms for the timeout.

Signed-off-by: Ronnie Sahlberg <ronniesahlberg@gmail.com>

lib/libnfs-sync.c

@@ -120,13 +120,10 @@ static void wait_for_reply(struct rpc_context *rpc, struct sync_cb_data *cb_data
 		pfd.fd = rpc_get_fd(rpc);
 		pfd.events = rpc_which_events(rpc);
 
-		ret = poll(&pfd, 1, rpc_get_timeout(rpc));
+		ret = poll(&pfd, 1, 100);
 		if (ret < 0) {
 			rpc_set_error(rpc, "Poll failed");
 			revents = -1;
-		} else if(ret == 0) {
-			rpc_set_error(rpc, "Timed out after [%d] milliseconds",rpc_get_timeout(rpc));
-			revents = -1;
 		} else {
 			revents = pfd.revents;
 		}