runc delete -f: fix for no pidns + no init case

Commit f8ad20f moved the kill logic from container destroy to container
kill (which is the right thing to do).

Alas, it broke the use case of doing "runc delete -f" for a container
which does not have its own private PID namespace, when its init process
is gone. In this case, some processes may still be running, and runc
delete -f should kill them (the same way as "runc kill" does).

It does not do that because the container status is "stopped" (as runc
considers the container with no init process as stopped), and so we only
call "destroy" (which was doing the killing before).

The fix is easy: if --force is set, call killContainer no matter what.

Add a test case, similar to the one in the previous commit.

Signed-off-by: Kir Kolyshkin <kolyshkin@gmail.com>

delete.go

@@ -66,6 +66,14 @@ status of "ubuntu01" as "stopped" the following will delete resources held for
 			}
 			return err
 		}
+		// When --force is given, we kill all container processes and
+		// then destroy the container. This is done even for a stopped
+		// container, because (in case it does not have its own PID
+		// namespace) there may be some leftover processes in the
+		// container's cgroup.
+		if force {
+			return killContainer(container)
+		}
 		s, err := container.Status()
 		if err != nil {
 			return err
@@ -76,9 +84,6 @@ status of "ubuntu01" as "stopped" the following will delete resources held for
 		case libcontainer.Created:
 			return killContainer(container)
 		default:
-			if force {
-				return killContainer(container)
-			}
 			return fmt.Errorf("cannot delete container %s that is not stopped: %s", id, s)
 		}