inmem: Receiver and Sender don't need to implement Close

Signed-off-by: Solomon Hykes <solomon@docker.com>

inmem/inmem.go

@@ -8,12 +8,10 @@ import (
 
 type Sender interface {
 	Send(msg *Message, mode int) (Receiver, Sender, error)
-	Close() error
 }
 
 type Receiver interface {
 	Receive(mode int) (*Message, Receiver, Sender, error)
-	Close() error
 }
 
 type Message struct {