MXS-1220: Allow modification of logging options

The logging options can now be modified with a PUT request.

server/core/maxscale/config_runtime.h

@@ -238,4 +238,13 @@ bool runtime_alter_monitor_from_json(MXS_MONITOR* monitor, json_t* new_json);
  */
 bool runtime_alter_service_from_json(SERVICE* service, json_t* new_json);
 
+/**
+ * @brief Alter logging options using JSON
+ *
+ * @param json JSON definition of the updated logging options
+ *
+ * @return True if the modifications were successful
+ */
+bool runtime_alter_logs_from_json(json_t* json);
+
 MXS_END_DECLS