Don't restrict lxc because of apparmor

We don't have the flexibility to do extra things with lxc because it is
a black box and most fo the magic happens before we get a chance to
interact with it in dockerinit.
Docker-DCO-1.1-Signed-off-by: Michael Crosby <michael@crosbymichael.com> (github: crosbymichael)

nsinit/init.go

@@ -79,7 +79,7 @@ func Init(container *libcontainer.Container, uncleanRootfs, consolePath string,
 		return fmt.Errorf("set process label %s", err)
 	}
 	if container.Context["restrictions"] != "" {
-		if err := restrict.Restrict(); err != nil {
+		if err := restrict.Restrict("proc", "sys"); err != nil {
 			return err
 		}
 	}

security/restrict/restrict.go

@@ -11,9 +11,9 @@ import (
 
 // This has to be called while the container still has CAP_SYS_ADMIN (to be able to perform mounts).
 // However, afterwards, CAP_SYS_ADMIN should be dropped (otherwise the user will be able to revert those changes).
-func Restrict() error {
+func Restrict(mounts ...string) error {
 	// remount proc and sys as readonly
-	for _, dest := range []string{"proc", "sys"} {
+	for _, dest := range mounts {
 		if err := system.Mount("", dest, "", syscall.MS_REMOUNT|syscall.MS_RDONLY, ""); err != nil {
 			return fmt.Errorf("unable to remount %s readonly: %s", dest, err)
 		}