Update containerd to ec15fe95aa.

Signed-off-by: Lantao Liu <lantaol@google.com>

vendor/github.com/Microsoft/hcsshim/processimage.go

@@ -0,0 +1,23 @@
+package hcsshim
+
+import "os"
+
+// ProcessBaseLayer post-processes a base layer that has had its files extracted.
+// The files should have been extracted to <path>\Files.
+func ProcessBaseLayer(path string) error {
+	err := processBaseImage(path)
+	if err != nil {
+		return &os.PathError{Op: "ProcessBaseLayer", Path: path, Err: err}
+	}
+	return nil
+}
+
+// ProcessUtilityVMImage post-processes a utility VM image that has had its files extracted.
+// The files should have been extracted to <path>\Files.
+func ProcessUtilityVMImage(path string) error {
+	err := processUtilityImage(path)
+	if err != nil {
+		return &os.PathError{Op: "ProcessUtilityVMImage", Path: path, Err: err}
+	}
+	return nil
+}