Function thread_pong

thread/test/test.cpp:334–344

thread_local static int volatile running = 0;
void* thread_pong(void* depth)
{
#ifdef RANDOMIZE_SP
    if (depth)
        return thread_pong((void*)((uint64_t)depth - 1));
#endif
    running = 1;
    while (running)
        thread_yield_fast();
    return nullptr;
}

int DevNull(void*, int);
void test_thread_switch(uint64_t nth, uint64_t stack_size)