hdf5_msb

[svn-r4964] Purpose:
    Change default actions.
Description:
    Change the default maximum number of processes (-P) to use all processes
    instead of just 1 (old default).  Someone most likely wants to test
    the I/O performance with all processes involved.
    Also starts performance measurement with maximum number of processes
    and decrement it with each loop.  If the performance measurement
    needs to restart, it can run with fewer processes if those loops
    have completed.
Platforms tested:
    modi4 and eirene.