Commits
Merging in latest from upstream (HDFFV/hdf5:refs/heads/hdf5_1_12) * commit '1097ac60c2b95a2b958a3150b537c75f512cacca': Merge t_2Gio test into hdf5_1_12. This will eventually be refactored out after merging the test functionality into the testphdf5 test. Merge t_2Gio test into hdf5_1_12. This will eventually be refactored out after merging the test functionality into the testphdf5 test. Minor tweaks noticed while going over VOL documentation. Yanked -Wc++-compat from the flags used to build the C library in both the Autotools and CMake. Fixed missing blob callbacks in test VOL connectors. Trivial parameter renaming in VOL API calls.
