The commit af8a7c13b5 has a problem that fsync returns EINVAL for
block device. This patch treats block devices as a special case.
https://cygwin.com/pipermail/cygwin/2023-January/252916.html
Fixes: af8a7c13b5 ("Cygwin: fsync: Return EINVAL for special files.")
Reported-by: Yano Ray <yanorei@hotmail.co.jp>
Reviewed-by: Corinna Vinschen <corinna@vinschen.de>
Signed-off-by: Takashi Yano <takashi.yano@nifty.ne.jp>