Close unused resource in dscreate and dsread. Otherwise, the file will not be close when close() is called.

See  the following for Delayed close, which is close dataset after exe terminate: https://www.hdfgroup.org/HDF5/doc/RM/RM_H5F.html#File-Close

change tab to 4 blanks

ensure that the double pass through CMakeLists.txt files do not generate double output

see https://github.com/Itseez/opencv/issues/6370

  - remove double-check, make MSVC happy