Update hcsshim and gowinio for Windows Overlay

vendor/github.com/Microsoft/hcsshim/internal/runhcs/util.go

@@ -0,0 +1,16 @@
+package runhcs
+
+import "net/url"
+
+const (
+	SafePipePrefix = `\\.\pipe\ProtectedPrefix\Administrators\`
+)
+
+// ShimSuccess is the byte stream returned on a successful operation.
+var ShimSuccess = []byte{0, 'O', 'K', 0}
+
+func SafePipePath(name string) string {
+	// Use a pipe in the Administrators protected prefixed to prevent malicious
+	// squatting.
+	return SafePipePrefix + url.PathEscape(name)
+}