Fix maintd crash when remote lsd dies unexpectedly.
Fix maintd crash when remote lsd dies unexpectedly.

Since the local lsd may take a few moments to notice that
a remote neighbor has passed on, the syncer may be unable to
connect to the remote node that lsd wants it to sync with.
If it can't get an aclnt, don't try to sync.

weidezhang/dht,weidezhang/dht,sit/dht,weidezhang/dht,sit/dht,weidezhang/dht,sit/dht,weidezhang/dht,sit/dht,sit/dht