Feature--to provide a standalone mode for t_mpi.c so that it can
be built outside of PHDF5 environment.
Description:
Move definitions that are common to all parallel test programs
to a new header file called testpar.h.
Leave only Parallel HDF5 tests related definitions in testphdf5.h.
Platforms tested:
heping (pp) and modi4(PP). Copper was down.
Misc. update:
