Websocket LWS keep servicing till no CB are left

Apparently, only a single WRITABLE/READABLE callback is called at each
servicing. For this reason, we want to keep servicing until we end up
not receiving any callback.
When that happens, we can assume that we can't (or don't want to) write
more, and that there is nothing left to read in the socket buffer.

modules/websocket/lws_helper.h

@@ -60,6 +60,7 @@ void _lws_make_protocols(void *p_obj, lws_callback_function *p_callback, PoolVec
 protected:															\
 	struct _LWSRef *_lws_ref;												\
 	struct lws_context *context;												\
+	bool _keep_servicing;													\
 																\
 	static int _lws_gd_callback(struct lws *wsi, enum lws_callback_reasons reason, void *user, void *in, size_t len) {	\
 																\
@@ -71,6 +72,7 @@ protected:															\
 		if (!ref->is_valid)												\
 			return 0;												\
 		CNAME *helper = (CNAME *)ref->obj;										\
+		helper->_keep_servicing = true;											\
 		return helper->_handle_cb(wsi, reason, user, in, len);								\
 	}															\
 																\
@@ -91,11 +93,14 @@ public:																\
 																\
 	void _lws_poll() {													\
 		ERR_FAIL_COND(context == NULL);											\
-																\
-		if (::_lws_poll(context, _lws_ref)) {										\
-			context = NULL;												\
-			_lws_ref = NULL;											\
-		}														\
+		do {														\
+			_keep_servicing = false;										\
+			if (::_lws_poll(context, _lws_ref)) {									\
+				context = NULL;											\
+				_lws_ref = NULL;										\
+				break;												\
+			}													\
+		} while (_keep_servicing);											\
 	}															\
 																\
 protected: