Reorganize test_mpi_specifyrowscolumns: #ifndef PV_USE_MPI wraps entire cpp file; if PV_USE_MPI is not defined all that's there is a two-line main file that prints an error message and exits with failure.
Reorganize test_mpi_specifyrowscolumns: #ifndef PV_USE_MPI wraps entire cpp file; if PV_USE_MPI is not defined all that's there is a two-line main file that prints an error message and exits with failure.

git-svn-id: 602a26e73ae9f2a14e2bb95676f2e137fcc39919@5530 7c0444ca-5550-0410-9008-faecdbe78eb5

dpaiton/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV,PetaVision/OpenPV,PetaVision/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,dpaiton/OpenPV,PetaVision/OpenPV