Update containerd dependencies for 1.2

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

vendor/github.com/containerd/cgroups/control.go

@@ -24,6 +24,7 @@ import (
 
 const (
 	cgroupProcs    = "cgroup.procs"
+	cgroupTasks    = "tasks"
 	defaultDirPerm = 0755
 )
 
@@ -48,8 +49,10 @@ type Process struct {
 type Cgroup interface {
 	// New creates a new cgroup under the calling cgroup
 	New(string, *specs.LinuxResources) (Cgroup, error)
-	// Add adds a process to the cgroup
+	// Add adds a process to the cgroup (cgroup.procs)
 	Add(Process) error
+	// AddTask adds a process to the cgroup (tasks)
+	AddTask(Process) error
 	// Delete removes the cgroup as a whole
 	Delete() error
 	// MoveTo moves all the processes under the calling cgroup to the provided one