internal/poll: remove detection of buggy splice on old Linux versions
internal/poll: remove detection of buggy splice on old Linux versions

The splice syscall is buggy prior to Linux 2.6.29. CL 113999 added a
workaround to detect buggy versions and disable use of splice for these.
As of Go 1.18 the minumum Linux version is 2.6.32. Thus, a non-buggy
implementation of the splice syscall can be assumed.

For #45964
Fixes #54505

Change-Id: Ied3a3334da7a3f7fa1280b7c5b1dfb9030219336
Reviewed-on: https://go-review.googlesource.com/c/go/+/422979
Reviewed-by: Ian Lance Taylor <87e9c6d529889242b7e184afb632328636553ab4@google.com>
TryBot-Result: Gopher Robot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Auto-Submit: Tobias Klauser <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>
Run-TryBot: Tobias Klauser <0a68dd4915066ec5d3f81f75a828fee53dcc8822@gmail.com>
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@golang.org>
Reviewed-by: Dmitri Shuralyov <d181b7fea0ec87c86ba5a890ab716db52498e3ba@google.com>

golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go,golang/go