logs not getting written when multiprocessing_context is spawn or forkserver

[krehm]

I just opened PR #130 to fix dlio.log so that it gets reopened in spawn and forkserver child processes so that the child log messages are not lost.

The same problem exists with dlp.log, but some of the code that needs to change is in repository dlio-profiler. Once that is updated and its release number is bumped, then changes can be made in dlio_benchmark to use the newer dlio-profiler version.