Fix more minor compiler warnings.

plugins/message-timestamp/mosquitto_message_timestamp.c

@@ -28,7 +28,7 @@ Contributors:
  *
  * Note that this only works on Mosquitto 2.0 or later.
  */
-
+#include "config.h"
 
 #include <stdio.h>
 #include <time.h>
@@ -47,6 +47,9 @@ static int callback_message(int event, void *event_data, void *userdata)
 	struct tm *ti;
 	char time_buf[25];
 
+	UNUSED(event);
+	UNUSED(userdata);
+
 	clock_gettime(CLOCK_REALTIME, &ts);
 	ti = gmtime(&ts.tv_sec);
 	strftime(time_buf, sizeof(time_buf), "%Y-%m-%dT%H:%M:%SZ", ti);
@@ -68,11 +71,19 @@ int mosquitto_plugin_version(int supported_version_count, const int *supported_v
 
 int mosquitto_plugin_init(mosquitto_plugin_id_t *identifier, void **user_data, struct mosquitto_opt *opts, int opt_count)
 {
+	UNUSED(user_data);
+	UNUSED(opts);
+	UNUSED(opt_count);
+
 	mosq_pid = identifier;
 	return mosquitto_callback_register(mosq_pid, MOSQ_EVT_MESSAGE, callback_message, NULL, NULL);
 }
 
 int mosquitto_plugin_cleanup(void *user_data, struct mosquitto_opt *opts, int opt_count)
 {
+	UNUSED(user_data);
+	UNUSED(opts);
+	UNUSED(opt_count);
+
 	return mosquitto_callback_unregister(mosq_pid, MOSQ_EVT_MESSAGE, callback_message, NULL);
 }