vchoi_fork

[svn-r20676] Purpose:
    - HDFFV-5928 - GMQS: h5diff problem and improvement on comparsing the same objects

Description:
    Fixed:
    1) adding h5tools_is_obj_same() function to check if two given IDs or paths point to the same object. This function can be very useful for other tools and applications.
    2) using h5tools_is_obj_same() at h5diff() and diff() in h5diff.c. If two paths point to the same object, there is no need to check the details of the object since we know there is no difference. The fix will increase the performance by skipping the content comparison. It also fixed the problem of reporting difference for some cases of comparing the same file, e.g. empty files or files with incomparable objects the same file.

    Test update:
    Updat prvious test cases (171, 172, 530) affected by this fix, so they
    still perfrom originally intended testing without bypassing.

Tested:
 jam (linux32-LE), koala (linux64-LE), heiwa (linuxppc64-BE), tejeda (mac32-LE), linew (solaris-BE), cmake