Method write_pod

src/core/impl/system.cpp:381–384

    template <class T>
    void write_pod(T val) {
        static_assert(std::is_pod<T>::value, "can only write POD");
        write(&val, sizeof(T));
    }

    void fork_exec_impl_mainloop(const char* arg) override {
        CHECK_SYS_ERR(prctl(PR_SET_PDEATHSIG, SIGKILL));