Ifpack_SparseContainer can't be used without initializing MPI

Created by: Sbte

Ifpack_SparseContainer can't be used when Trilinos is compiled with MPI support but it is used without calling MPI_Initialize. This happens because a serial MPI communicator is instantiated in the constructor:

https://github.com/trilinos/Trilinos/blob/master/packages/ifpack/src/Ifpack_SparseContainer.h#L323

A case where one might want to use this without calling MPI_Initialize is when Epetra_SerialComm is used for all vectors and matrices. Is there any reason why Epetra_MpiComm(MPI_COMM_SELF) is used instead of Epetra_SerialComm in Ifpack_SparseContainer? If not I can submit a pull request that gets rid of this if you like.