hdf5_msb

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

* commit '4830a1796441abbb5a4fbd2cff9a651f2a0d066e':
  Updated tools dump output when dataset offset is undefined.
  Added checks for native optional call support in some of the tools.
  Misc changes for h5dump VOL changes.