* added cfoa_interprocess_concurrency_tests
* avoided C++14 digit separators
* stopped using exit codes to pass numerical info to parent
* Reorder includes to make msvc-14.0 happy
* made cumulative_stats interprocess concurrency safe
* disabled interprocess_concurrency_tests for Clang 3.5-8
(Boost.Process compile error)
* made test names shorter for the benefit of MINGW32
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Co-authored-by: Peter Dimov <pdimov@gmail.com>
