hdf5_msb

[svn-r24142] Purpose: Fix bug in tests
Description:
    - Passing the c_str() of an std string into a C function caused failure
      on OpenVMS.  Added a work around using temporary string. (th5s.cpp)
    - Passing incorrect file access property list caused test_datasize() to
      fail.  Fixed.
    - Close a group in test_dset, before the file can be properly closed.
      This should fix the problem on OpenVMS.
Platforms tested:
    Linux/32 2.6 (jam)
    SunOS 5.11 (emu)
    Linux/ppc64 (ostrich)