compliation error

Figured this out finally. It's b/c the OpenMPI
mpi.h must include stdint.h somewhere and if
it does, it includes it without the proper #define
in place that pulls in its 64-bit definitions like
lmptype.h insures.

So a *,cpp file that includes mpi.h needs to
also include lmptype.h before mpi.h, else
it is too late when it gets pulled in afterwards
via the normal LAMMPS class includes.

I guess it is bad design for system include
file like stdint.h to have definitions that depend
on pre-defined settings, because once
its been included you can never get the ones
you want later.