hdf5_ep

[svn-r21892] Purpose:
  Fix for HDFFV-7836 h5diff: displays error stack message for comparing the two dangling symlink with follow-symlinks option

Description:
  While ago, to improve performance, skipping same object checking 
  (h5tools_is_obj_same()) was added. 
  However the checking function doesn't understand about the dangling link and
  caused the issue. 
  Since handling dangling link code section already implemented, move the 
  checking function after handling dangling-links to address the problem.
  Test was added and tagged with jira#.

Tested:
  jam (linux32-LE), koala (linux64-LE), ostrich (linuxppc64-BE), tejeda (mac32-LE), linew (solaris-BE),  Windows (32-LE cmake), Cmake (jam)