hdf5_ep

[svn-r1335] h5toh4 test script used to compare the output of hdp applied on
the generanted hdf files against saved output of hdp.  This did not
work well because whenever the hdp changes its output format, the
tests failed unnecessarily.  The tests also failed if the test machine
uses a different version of HDF library from the HDF5 development
machine.

Changed the algorithm to compare the generated HDF files against
saved HDF files (first by a simple cmp; if that fails, compare the
output of the host machine's hdp on both HDF files.)

Tested on Hawkwind (FreeBSD) with srcdir option and Baldric (Solaris)
without srcdir option.