Dawn easy benchmark for C++

bench.h

#ifdef BENCH
#include <ctime>
#include <chrono>
#define BENCHMARK_START \
    auto t_start = std::chrono::high_resolution_clock::now(); \
    std::clock_t c_start = std::clock();
#define BENCHMARK_FINISH( OUT_STREAM, NAME ) \
    std::clock_t c_end = std::clock(); \
    auto t_end = std::chrono::high_resolution_clock::now(); \
    OUT_STREAM   << "BENCHMARK \"" << NAME << "\" : " \
                 << std::fixed << "CPU time: " \
                 << 1000.0 * (c_end-c_start) / CLOCKS_PER_SEC << " ms; " \
                 << "Wall time: " \
                 << std::chrono::duration<double, std::milli>(t_end-t_start).count() \
                 << " ms\n";
#else
#define BENCHMARK_START 
#define BENCHMARK_FINISH( OUT_STREAM, NAME )
#endif