Zoltan2: add additional guards when using Epetra code from Xpetra
Created by: aprokop
It is possible to configure Trilinos with HAVE_ZOLTAN2_EPETRA=ON, but HAVE_XPETRA_EPETRA=OFF. Such a configuration means that one cannot actually run Xpetra::Epetra code in Zoltan2.
@trilinos/zoltan2