libplugin: add command_hook_success helper.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>

plugins/libplugin.c

@@ -1595,3 +1595,11 @@ struct route_hop *json_to_route(const tal_t *ctx, const char *buffer,
 	}
 	return hops;
 }
+
+struct command_result *WARN_UNUSED_RESULT
+command_hook_success(struct command *cmd)
+{
+	struct json_stream *response = jsonrpc_stream_success(cmd);
+	json_add_string(response, "result", "continue");
+	return command_finished(cmd, response);
+}

plugins/libplugin.h

@@ -186,6 +186,10 @@ command_success(struct command *cmd, const struct json_out *result);
 struct command_result *WARN_UNUSED_RESULT
 command_success_str(struct command *cmd, const char *str);
 
+/* End a hook normally (with "result": "continue") */
+struct command_result *WARN_UNUSED_RESULT
+command_hook_success(struct command *cmd);
+
 /* Synchronous helper to send command and extract single field from
  * response; can only be used in init callback. */
 const char *rpc_delve(const tal_t *ctx,