Function measure

lib/catch2/catch.hpp:6842–6848

        namespace Detail {
            template <typename Clock, typename Fun, typename... Args>
            TimingOf<Clock, Fun, Args...> measure(Fun&& fun, Args&&... args) {
                auto start = Clock::now();
                auto&& r = Detail::complete_invoke(fun, std::forward<Args>(args)...);
                auto end = Clock::now();
                auto delta = end - start;
                return { delta, std::forward<decltype(r)>(r), 1 };
            }
        } // namespace Detail
    } // namespace Benchmark
} // namespace Catch