ELPA can now be linked against a 64bit integer version of MPI and
ScalaPack. This is an experimental feature

The following points are still to be done
- does not work with real QR-decomposition
- generalized routines return wrong results
- the C tests and the C Cannon algorithm implementation do not
  work (no 64bit header files for MPI *at least* with Intel MPI)

ELPA can now link agains a 64bit integer verion of BLAS/LAPACK.
Currently this only works if ELPA is compiled with MPI=OFF!

The 64bit support is not available in the legacy interface