Revert "internal/poll: drop redundant ENOSYS in CopyFileRange"
This reverts CL 428555.
Reason for revert: It appears that even a newer kernel can get
ENOSYS from copy_file_range.
Fixes #58592
Change-Id: Ib8dd1be61544f54bf652a99dc0b449109f8f50ed
Reviewed-on: https://go-review.googlesource.com/c/go/+/470016 Reviewed-by: Andy Pan <panjf2000@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Ian Lance Taylor <iant@golang.org> Reviewed-by: Than McIntosh <thanm@google.com> Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Tobias Klauser <tobias.klauser@gmail.com>