Remove dependency on tar2vhd for LCOW differ

This change no longer requires the use of a UtlityVM on Windows to convert the
layer tar to an ext4 vhd for LCOW. This has a significant performance boost
that makes linux/amd64 layer extraction comparable to native Linux performance.

Signed-off-by: Justin Terry (VM) <juterry@microsoft.com>

vendor/github.com/Microsoft/hcsshim/cmd/go-runhcs/runhcs.go

@@ -10,6 +10,7 @@ import (
 	"strings"
 	"sync"
 
+	irunhcs "github.com/Microsoft/hcsshim/internal/runhcs"
 	"github.com/containerd/go-runc"
 )
 
@@ -23,8 +24,7 @@ const (
 	// JSON is the JSON formatted log output.
 	JSON Format = "json"
 
-	command        = "runhcs"
-	safePipePrefix = `\\.\pipe\ProtectedPrefix\Administrators\`
+	command = "runhcs"
 )
 
 var bytesBufferPool = sync.Pool{
@@ -62,7 +62,7 @@ func (r *Runhcs) args() []string {
 		out = append(out, "--debug")
 	}
 	if r.Log != "" {
-		if strings.HasPrefix(r.Log, safePipePrefix) {
+		if strings.HasPrefix(r.Log, irunhcs.SafePipePrefix) {
 			out = append(out, "--log", r.Log)
 		} else {
 			abs, err := filepath.Abs(r.Log)

vendor/github.com/Microsoft/hcsshim/cmd/go-runhcs/runhcs_create.go

@@ -6,6 +6,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	irunhcs "github.com/Microsoft/hcsshim/internal/runhcs"
 	runc "github.com/containerd/go-runc"
 )
 
@@ -32,7 +33,7 @@ func (opt *CreateOpts) args() ([]string, error) {
 		out = append(out, "--pid-file", abs)
 	}
 	if opt.ShimLog != "" {
-		if strings.HasPrefix(opt.ShimLog, safePipePrefix) {
+		if strings.HasPrefix(opt.ShimLog, irunhcs.SafePipePrefix) {
 			out = append(out, "--shim-log", opt.ShimLog)
 		} else {
 			abs, err := filepath.Abs(opt.ShimLog)
@@ -43,7 +44,7 @@ func (opt *CreateOpts) args() ([]string, error) {
 		}
 	}
 	if opt.VMLog != "" {
-		if strings.HasPrefix(opt.VMLog, safePipePrefix) {
+		if strings.HasPrefix(opt.VMLog, irunhcs.SafePipePrefix) {
 			out = append(out, "--vm-log", opt.VMLog)
 		} else {
 			abs, err := filepath.Abs(opt.VMLog)

vendor/github.com/Microsoft/hcsshim/cmd/go-runhcs/runhcs_exec.go

@@ -6,6 +6,7 @@ import (
 	"path/filepath"
 	"strings"
 
+	irunhcs "github.com/Microsoft/hcsshim/internal/runhcs"
 	"github.com/containerd/go-runc"
 )
 
@@ -33,7 +34,7 @@ func (opt *ExecOpts) args() ([]string, error) {
 		out = append(out, "--pid-file", abs)
 	}
 	if opt.ShimLog != "" {
-		if strings.HasPrefix(opt.ShimLog, safePipePrefix) {
+		if strings.HasPrefix(opt.ShimLog, irunhcs.SafePipePrefix) {
 			out = append(out, "--shim-log", opt.ShimLog)
 		} else {
 			abs, err := filepath.Abs(opt.ShimLog)