Looks up or registers a flags type that is implemented with a particular type plugin. If a type with name type_name was previously registered, the GType identifier for the type is returned, otherwise the type is newly registered, and the resulting GType identifier returned.
As long as any instances of the type exist, the type plugin will not be unloaded.
Since 2.56 if module is NULL this will call g_type_register_static() instead. This can be used when making a static build of the module.