hdf5_msb

Merging in latest from upstream (HDFFV/hdf5:refs/heads/develop)

* commit '4643860aa940fb52da251f7023ec2e48d7d10f34':
  HDFFV-10635: Some minor changes to the test case and the comments in the library.
  HDFFV-10635: add a test case.
  HDFFV-10635: Allowing to write the same variable-length element more than once.