Update Vendor

(*) github.com/Microsoft/hcsshim
    (*) golang.org/x/sys
    (*) github.com/x/cyrpto
    (*) github.com/sirupsen/logrus
    (*) github.com/Microsoft/go-winio
    (*) github.com/juju/errors
    (*) github.com/buger/jsonparser

vendor/github.com/Microsoft/hcsshim/internal/wclayer/preparelayer.go

@@ -0,0 +1,40 @@
+package wclayer
+
+import (
+	"sync"
+
+	"github.com/Microsoft/hcsshim/internal/hcserror"
+	"github.com/sirupsen/logrus"
+)
+
+var prepareLayerLock sync.Mutex
+
+// PrepareLayer finds a mounted read-write layer matching path and enables the
+// the filesystem filter for use on that layer.  This requires the paths to all
+// parent layers, and is necessary in order to view or interact with the layer
+// as an actual filesystem (reading and writing files, creating directories, etc).
+// Disabling the filter must be done via UnprepareLayer.
+func PrepareLayer(path string, parentLayerPaths []string) error {
+	title := "hcsshim::PrepareLayer "
+	logrus.Debugf(title+"path %s", path)
+
+	// Generate layer descriptors
+	layers, err := layerPathsToDescriptors(parentLayerPaths)
+	if err != nil {
+		return err
+	}
+
+	// This lock is a temporary workaround for a Windows bug. Only allowing one
+	// call to prepareLayer at a time vastly reduces the chance of a timeout.
+	prepareLayerLock.Lock()
+	defer prepareLayerLock.Unlock()
+	err = prepareLayer(&stdDriverInfo, path, layers)
+	if err != nil {
+		err = hcserror.Errorf(err, title, "path=%s", path)
+		logrus.Error(err)
+		return err
+	}
+
+	logrus.Debugf(title+"succeeded path=%s", path)
+	return nil
+}