net/tstun: probe TCP GRO (#13376)

Disable TCP & UDP GRO if the probe fails.

torvalds/linux@e269d79c7d broke virtio_net
TCP & UDP GRO causing GRO writes to return EINVAL. The bug was then
resolved later in
torvalds/linux@89add40066. The offending
commit was pulled into various LTS releases.

Updates #13041

Signed-off-by: Jordan Whited <jordan@tailscale.com>

net/tstun/wrap_noop.go

@@ -0,0 +1,8 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+//go:build !linux
+
+package tstun
+
+func (t *Wrapper) SetLinkFeaturesPostUp() {}