hdf5_chunking_query_bmr

Merge pull request #938 in HDFFV/hdf5 from avoid_trunc_beta to develop

* commit '4823abf3ee0d9df1c3f23ae7e36ce4d1d146afd6':
  Removed commented out code from H5FDmpio.c, H5FDprivate.h and H5Fint.c
  Optimized version of avoid truncate patch.