Merge pull request #2871 in HDFFV/hdf5 from fix_nil_collective_metadata_write_1_12 to hdf5_1_12
* commit '8b48ddb4c8d02aec2bc5e938fe7b789f6ad9c2b2':
Add release note for collective metadata fix
Fix mis-merge from develop
Update buffer count
Revert " Checkin of fix for CGNS bug"
Revert "Removed commeted out code from H5C_dump_coll_write_list()"
