os,internal/poll: support I/O on overlapped files not added to the poller
This fixes the support for I/O on overlapped files that are not added to
the poller. Note that CL 661795 already added support for that, but it
really only worked for pipes, not for plain files.
Additionally, this CL also makes this kind of I/O operations to not
notify the external poller to avoid confusing it.
Updates #15388.
Change-Id: I15c6ea74f3a87960aef0986598077b6eab9b9c99
Reviewed-on: https://go-review.googlesource.com/c/go/+/664415
LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Reviewed-by: Michael Pratt <mpratt@google.com> Reviewed-by: Alex Brainman <alex.brainman@gmail.com> Reviewed-by: Damien Neil <dneil@google.com>
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