bufio: permit r.Reset(r) without infinite recursion
This can happen in reasonable code because NewReader(r) can return r,
if r is already a Reader.
Similarly for Writer.
Fixes #58423
Change-Id: Iff9d9265410bee68fbaeb7175369847bd737eb2c
Reviewed-on: https://go-review.googlesource.com/c/go/+/466815 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com> Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>