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/hardlink_unix.go

@@ -0,0 +1,34 @@
+// +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 (
+	"os"
+	"syscall"
+)
+
+func getLinkInfo(fi os.FileInfo) (uint64, bool) {
+	s, ok := fi.Sys().(*syscall.Stat_t)
+	if !ok {
+		return 0, false
+	}
+
+	// Ino is uint32 on bsd, uint64 on darwin/linux/solaris
+	return uint64(s.Ino), !fi.IsDir() && s.Nlink > 1 // nolint: unconvert
+}