hdf5_chunking_query_bmr

Merge pull request #207 in HDFFV/hdf5 from ~KOZIOL/hdf5:develop_swmr_merge_06 to develop

* commit 'f8cfbee05e26a815134cd1f1fb0ad87d8d9b16dd':
  Merge SWMR-related testing to existing tests.
  Bring over tweak for missing environment variable.
  Update CMake configuration files with SWMR accumulator changes.
  Add missing accumulator test.
  Merge SWMR-oriented accumulator tests from revise_chunks to develop.