internal/poll: treat copy_file_range EOPNOTSUPP as not-handled
internal/poll: treat copy_file_range EOPNOTSUPP as not-handled

Fixes #40731

Change-Id: I3e29878d597318acf5edcc38497aa2624f72be35
Reviewed-on: https://go-review.googlesource.com/c/go/+/248258
Run-TryBot: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@golang.org>
TryBot-Result: Gobot Gobot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Emmanuel Odeke <277f8eaa8c7dfbc55c17bf5e30561c1a9c45c569@gmail.com>
Reviewed-by: Tobias Klauser <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>

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