nss: refuse previously loaded certificate from file

... when we are not asked to use a certificate from file
static void nss_destroy_object(void *user, void *ptr)
{
  PK11GenericObject *obj = (PK11GenericObject *)ptr;
  (void) user;
  PK11_DestroyGenericObject(obj);
}

static void nss_destroy_object(void *user, void *ptr)
{
  PK11GenericObject *obj = (PK11GenericObject *)ptr;
  (void) user;
  PK11_DestroyGenericObject(obj);
}
