os: plan9 seek() should invalidate cached directory info
os: plan9 seek() should invalidate cached directory info

Update #37161

Change-Id: Iee828bbcc8436af29ca6dd9ed897cb5265a57cf8
Reviewed-on: https://go-review.googlesource.com/c/go/+/221778
Run-TryBot: Keith Randall <8c99c3a9284e493be632950b84cd789d08ed3e9d@golang.org>
Reviewed-by: Emmanuel Odeke <277f8eaa8c7dfbc55c17bf5e30561c1a9c45c569@gmail.com>

golang/go,nawawi/go,CAFxX/go,cloudflare/go,golang/go,nawawi/go,nawawi/go,akutz/go,cloudflare/go,CAFxX/go,nawawi/go,cloudflare/go,CAFxX/go,golang/go,cloudflare/go,golang/go,nawawi/go,akutz/go,akutz/go,cloudflare/go,cloudflare/go,akutz/go,CAFxX/go,akutz/go,CAFxX/go,golang/go,cloudflare/go,akutz/go,golang/go,CAFxX/go,akutz/go,akutz/go,golang/go,CAFxX/go,nawawi/go,CAFxX/go,nawawi/go,nawawi/go,golang/go,cloudflare/go