CoreMarkCpp

Simplified code from https://github.com/eembc/coremark.

The benchmark algorithm, setup and parameters are unchanged, so the results should be 100% comparable with the original CoreMark benchmark, provided that CoreMark is compiled with MULTITHREAD symbol value equal to the number of CPU cores on the system. However, the original README.md clearly states that changing anything outside of core_portme* is NOT ALLOWED, and I broke that, obviously.

I made the following modifications:

• Replaced make build with CMake.
• Reformatted using clang-format.
• Removed platform-specific C code, replaced with portable C++, specifically:
  • replaced fork/socket/pthread with C++ std::thread,
  • replaced time measurement with std::chrono::steady_clock::now,
  • added detection of the number of CPU cores using std::thread::hardware_concurrency.
• Split the original coremark.h into individual header files matching the cpp content, also used IWYU.