am 91cf41cf: init: wait_for_file use smaller time resolution

int wait_for_file(const char *filename, int timeout)

{

    struct stat info;

    time_t timeout_time = gettime() + timeout;

    uint64_t timeout_time_ns = gettime_ns() + timeout * UINT64_C(1000000000);

    int ret = -1;

    while (gettime() < timeout_time && ((ret = stat(filename, &info)) < 0))

    while (gettime_ns() < timeout_time_ns && ((ret = stat(filename, &info)) < 0))

        usleep(10000);

    return ret;