Within some set of compiler/MPI lib letting cmake compiles on the fly
the ParMetis/src/setType/test.cc program that set types for Parmetis is
rather cumbersome. To simplify compilation/running context of this
program this commit removes MPI context usage. This little testing
program is now a pure sequential application where mpi.h header is used
due to Parmetis header usage.
set to null ptr to avoid warning with potential uninitialized value.