Sentinel: fixed a crash on script execution.

The call to sentinelScheduleScriptExecution() lacked the final NULL
argument to signal the end of arguments. This resulted into a crash.

src/sentinel.c

@@ -789,7 +789,7 @@ void sentinelCallClientReconfScript(sentinelRedisInstance *master, int role, cha
     sentinelScheduleScriptExecution(master->client_reconfig_script,
         master->name,
         (role == SENTINEL_LEADER) ? "leader" : "observer",
-        state, from->ip, fromport, to->ip, toport);
+        state, from->ip, fromport, to->ip, toport, NULL);
 }
 
 /* ========================== sentinelRedisInstance ========================= */