hdf5_ep

[svn-r3717] Purpose:
    new test
Description:
    Added two new tests.
    test_mpio_offset:
	Verify that MPI_Offset exceeding 2**31 can be computed correctly.
    test_mpio_gb_file
	Test if MPIO can write file from under 2GB to over 2GB and then
	from under 4GB to over 4GB.
Platforms tested:
    modi4(-64), tflops.