hdf5_msb

[svn-r15043] Bug fix.

Description:
perf would crash at the end as it complained it was doing MPI calls after
MPI_Finalize() is called.  I suspect the HDF5 library is making MPI calls
in the at_exit area.  This should not happened.

Solution:
Added the H5exit() right before MPI_Finalize() fixed the problem.
But it needs to find out why HDF5 library is making MPI calls in
the at_exit() area.  It should not.
Also, changed the temporay data file name from /tmp/test.out to
perftest.out, both to avoid multiple instance of this may use the
same /tmp/xxx name and also make the file name less generic.

Tested:
Kagiso PP.