Add LWS_PROTOCOL_LIST_TERM compat for older libwebsockets

Ubuntu 22.04 ships libwebsockets < 4.1 which does not define
LWS_PROTOCOL_LIST_TERM. Add a fallback define in both the broker
and the websocket client so CI builds succeed.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: embhorn

examples/websocket/net_libwebsockets.c

@@ -33,6 +33,11 @@
 
 #include <libwebsockets.h>
 
+/* Compatibility for older libwebsockets versions (pre-4.1) */
+#ifndef LWS_PROTOCOL_LIST_TERM
+    #define LWS_PROTOCOL_LIST_TERM { NULL, NULL, 0, 0, 0, NULL, 0 }
+#endif
+
 /* Network context for libwebsockets */
 typedef struct _LibwebsockContext {
     struct lws_context *context;

src/mqtt_broker.c

@@ -465,6 +465,11 @@ static void BrokerTls_Free(MqttBroker* broker)
 
 #include <libwebsockets.h>
 
+/* Compatibility for older libwebsockets versions (pre-4.1) */
+#ifndef LWS_PROTOCOL_LIST_TERM
+    #define LWS_PROTOCOL_LIST_TERM { NULL, NULL, 0, 0, 0, NULL, 0 }
+#endif
+
 /* Forward declaration for the no-op connect callback (defined after WS section) */
 static int BrokerNetConnect(void* context, const char* host, word16 port,
     int timeout_ms);