7177409: Perf regression in JVM_GetClassDeclaredFields after generic signature changes. Summary: In fieldDescriptor::generic_signature() returns NULL immediately if the field has no generic signature. Reviewed-by: dholmes, coleenp, jcoomes

// A simple interface, to allow an unknown foreign call from a class
// loaded with LOADER1 to a class loaded with LOADER2.
public interface IFace {
  public many_loader[] gen();
}