Merge pull request #120 in HDF5VOL/daos-vol from ~NFORTNE2/daos-vol:auto_chunk to master
* commit '34f3d46384456b4959c033ebc97fa1b0e7318f20':
Add env var H5_DAOS_CHUNK_TARGET_SIZE for configuring target chunk size for automatic chunking.
Change rounding cutoff for nchunks calculation for 1/2 to 1/3, to minimize the chance that rounding in chunk dims causes the chunk to be bigger than ideal. Still an approximation.
Switch to using integer modulus for rounding in nchunks calculation for automatic chunk sizing.
Switch auto chunk algorithm to use floating point math where appropriate. Fix issue where chunk size was not saved to DCPL.
Add automatic chunk sizing. Target size currently hardcoded to 1 MB.
