hdf5

Merge pull request #2445 in HDFFV/hdf5 from alloc_stats to develop

* commit 'b51585a9110c4322c52f9dcdc60cd26c3ea44546':
  Revise API for H5get_alloc_stats() to take a struct instead of separate values.
  Add routines to query the library's free list sizes and allocation stats.