hdf5_ep

[svn-r20469] Bug 1386 - allow dimension size to be zero even though it isn't unlimited.  This is a follow-up checkin for r20440:
  1. I added a test case of extending dataset of zero dimension size and shrinking back to zero dimension size.
  2. I updated the Makefile to include the new data file to be cleaned up.

Tested on jam - relatively simple.