Remove sigchld reaper from containerd process

Because we are launching alot of different runc commands to do
operations there is a race between doing a `cmd.Wait()` and getting the
sigchld and reaping it.  We can remove the sigchild reaper from
containerd as long as we make sure we reap the shim process if we are
the parent, i.e. not restored.

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

supervisor/sort_test.go

@@ -61,6 +61,10 @@ func (p *testProcess) State() runtime.State {
 	return runtime.Running
 }
 
+func (p *testProcess) Wait() {
+
+}
+
 func TestSortProcesses(t *testing.T) {
 	p := []runtime.Process{
 		&testProcess{"ls"},

supervisor/supervisor.go

@@ -274,6 +274,7 @@ func (s *Supervisor) SendTask(evt Task) {
 
 func (s *Supervisor) exitHandler() {
 	for p := range s.monitor.Exits() {
+		p.Wait()
 		e := &ExitTask{
 			Process: p,
 		}