tool_util.c: Use GetTickCount64 if it is available

  ** GetTickCount() is available on _all_ Windows versions from W95 up

  ** to nowadays. Returns milliseconds elapsed since last system boot,

  ** increases monotonically and wraps once 49.7 days have elapsed.

  **

  ** GetTickCount64() is available on Windows version from Windows Vista

  ** and Windows Server 2008 up to nowadays. The resolution of the

  ** function is limited to the resolution of the system timer, which

  ** is typically in the range of 10 milliseconds to 16 milliseconds.

  */

  struct timeval now;

#if defined(_WIN32_WINNT) && (_WIN32_WINNT >= 0x0600)

  ULONGLONG milliseconds = GetTickCount64();

#else

  DWORD milliseconds = GetTickCount();

  now.tv_sec = milliseconds / 1000;

#endif

  now.tv_sec = (long)(milliseconds / 1000);

  now.tv_usec = (milliseconds % 1000) * 1000;

  return now;

}