hdf5_plugins

Merge pull request #160 in TEST/hdf5_plugins from ~BYRN/hdf5_plugins_adb:master to master

* commit 'f641f2c06f8b1e77c4ab27fb0c7cbe0f5f3c0edc':
  Add missing macro call for single option
  Remove extra if block
  Fix and remove duplicate macros
  Remove old macro reference