hdf5_ep

[svn-r23427] Purpose: Fix bug HDFFV-8067
Description:
  + The C++ test failed with the new PGI compilers versions 12.4 and 12.5
  + An exception thrown by an internal function, which was called by
    a constructor, was not propagating to the test program during the stack
    unwinding, so it couldn't be caught by the test and the program terminated.
  + Various trials and errors indicated that the problem is where an STD string
    converted to a char* being passed to the internal function, but confirmation
    has not been found yet.  It could be a compiler bug.
Solution:
  + Added a try/catch in the constructor around the internal function and
    re-throw the exception when it is caught.  This is a workaround.
  + Unrelated minor fixes: removed unused variables and MESSAGE's; commented
    out tvlstr.cpp/test_read_vl_string_attribute because it may be redundant,
    and commented out H5Tpkg.h inclusion because TEST_ALIGNMENT is not added
    yet and probably not necessary in the C++ API.
Platforms tested:
    Linux/32 2.6 (jam) with PGI compilers
    Linux/32 2.6 (jam) with GNU compilers
    Linux/64 2.6 (koala)