internal/poll: clear completed Buffers to permit earlier collection
Updates #45163
Change-Id: I73a6f22715550e0e8b83fbd3ebec72ef019f153f
Reviewed-on: https://go-review.googlesource.com/c/go/+/373374
Run-TryBot: Lee Baokun <bk@golangcn.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@google.com> Reviewed-by: Carlos Amedee <carlos@golang.org> Reviewed-by: Ian Lance Taylor <iant@google.com>