Use select in TLCP client

Example of `tlcp_client`

```
$ gmssl tlcp_client -host ebssec.boc.cn
Connection established!
GET / HTTP/1.1[enter]
Host: localhost[enter]
[enter]
[enter]
```

src/tlcp.c

@@ -595,7 +595,7 @@ int tlcp_do_connect(TLS_CONNECT *conn)
 		tls_send_alert(conn, TLS_alert_decrypt_error);
 		goto end;
 	}
-	tls_trace("Connection established!\n");
+	printf("Connection established!\n");
 
 
 	conn->protocol = TLS_protocol_tlcp;