fixed ssserver reporting to manager listening on UDS

- fixes #649

Author: zonyitoo

crates/shadowsocks/src/manager/datagram.rs

@@ -97,7 +97,11 @@ impl ManagerDatagram {
             #[cfg(unix)]
             // For unix socket, it doesn't need to bind to any valid address
             // Because manager won't response to you
-            ManagerAddr::UnixSocketAddr(..) => Ok(ManagerDatagram::UnixDatagram(UnixDatagram::unbound()?)),
+            ManagerAddr::UnixSocketAddr(ref path) => {
+                let dgram = UnixDatagram::unbound()?;
+                dgram.connect(path)?;
+                Ok(ManagerDatagram::UnixDatagram(dgram))
+            }
         }
     }