chore(deps): cleanup go.mod a little bit (#136)

* Upgrade docker to v19.03.7

* go mod vendor

* golangci-lint 1.23.8

vendor/github.com/containerd/continuity/fs/du_windows.go

@@ -0,0 +1,82 @@
+// +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 fs
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+)
+
+func diskUsage(ctx context.Context, roots ...string) (Usage, error) {
+	var (
+		size int64
+	)
+
+	// TODO(stevvooe): Support inodes (or equivalent) for windows.
+
+	for _, root := range roots {
+		if err := filepath.Walk(root, func(path string, fi os.FileInfo, err error) error {
+			if err != nil {
+				return err
+			}
+
+			select {
+			case <-ctx.Done():
+				return ctx.Err()
+			default:
+			}
+
+			size += fi.Size()
+			return nil
+		}); err != nil {
+			return Usage{}, err
+		}
+	}
+
+	return Usage{
+		Size: size,
+	}, nil
+}
+
+func diffUsage(ctx context.Context, a, b string) (Usage, error) {
+	var (
+		size int64
+	)
+
+	if err := Changes(ctx, a, b, func(kind ChangeKind, _ string, fi os.FileInfo, err error) error {
+		if err != nil {
+			return err
+		}
+
+		if kind == ChangeKindAdd || kind == ChangeKindModify {
+			size += fi.Size()
+
+			return nil
+
+		}
+		return nil
+	}); err != nil {
+		return Usage{}, err
+	}
+
+	return Usage{
+		Size: size,
+	}, nil
+}