h5compat

Merging in latest from upstream (OTHER/h5compat:refs/heads/master)

* commit '7e924dbee06e4b880e9ef1fe1fc121c8995db8a5':
  (1) Combine tests/t_ref_object.c and tests/t_ref_region.c into tests/t_ref.c (2) Fix bug when reading the referenced datasets