hdf5_msb

[svn-r4748] Purpose:
    Bug fix
Description:
    All processes, including those that are not part of the PIO test
    sub-communicator, all attempted to run the PIO test.  It resulted
    in failures for those processes that are not supposed to get involved.
Solution:
    The function that creates the sub-communicator also returns a
    parameter indicating if the process is included in the PIO test
    sub-communicator.  Then only those processes will really do the
    PIO test.
Platforms tested:
    eirene (pp) and Modi4 (pp)