hdf5_der

Merge pull request #142 in HDFFV/hdf5 from ~DEROBINS/hdf5_der:revise_chunks to revise_chunks

Fixes compilation problems on Windows (log VFD, missing timespec on VS2013 and earlier).

* commit '7fcf33c63d6fbe3fd8630728614a98ec31bb7fa4':
  Fixes Windows compilation errors.