ethcore: fix rlp deprecation warnings (#11280)

ethcore/sync/src/chain/mod.rs

@@ -1258,7 +1258,7 @@ impl ChainSync {
 				packet.append(&self.private_tx_handler.is_some());
 			}
 		}
-		packet.complete_unbounded_list();
+		packet.finalize_unbounded_list();
 		io.respond(StatusPacket.id(), packet.out())
 	}
 

ethcore/sync/src/chain/propagator.rs

@@ -222,7 +222,7 @@ impl SyncPropagator {
 						pushed += 1;
 					}
 				}
-				packet.complete_unbounded_list();
+				packet.finalize_unbounded_list();
 				(packet, to_send)
 			};