socketpair_windows: remove implementation for now

Current implementation has the same issues that
socketpair_unix.go had, namely double closes and
leaking FDs. The initial author prefers to remove
the code for now as the whole feature (NRI) doesn't
work on windows for now.

This allows us to rename socketpair_unix.go -> socketpair.go
as everything in it is generic.

Signed-off-by: Etienne Champetier <e.champetier@ateme.com>

pkg/net/socketpair_unix.go → pkg/net/socketpair.go

@@ -1,5 +1,3 @@
-//go:build !windows
-
 /*
    Copyright The containerd Authors.
 

pkg/net/socketpair_cloexec_windows.go

@@ -0,0 +1,30 @@
+//go:build windows
+
+/*
+   Copyright The containerd Authors.
+
+   Licensed under the Apache License, Version 2.0 (the "License");
+   you may not use this file except in compliance with the License.
+   You may obtain a copy of the License at
+
+       http://www.apache.org/licenses/LICENSE-2.0
+
+   Unless required by applicable law or agreed to in writing, software
+   distributed under the License is distributed on an "AS IS" BASIS,
+   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+   See the License for the specific language governing permissions and
+   limitations under the License.
+*/
+
+package net
+
+import (
+	"errors"
+
+	sys "golang.org/x/sys/windows"
+)
+
+func newSocketPairCLOEXEC() ([2]sys.Handle, error) {
+	// when implementing do use WSA_FLAG_NO_HANDLE_INHERIT to avoid leaking FDs
+	return [2]sys.Handle{sys.InvalidHandle, sys.InvalidHandle}, errors.New("newSocketPairCLOEXEC unimplemented for windows")
+}