Fixing apicheck to cope with interfaces inherited from other interfaces.

For example, in Java 5, FutureTask was declared like this:
    public class FutureTask<V> implements Runnable, Future<V> {}

In Java 6, it's declared like this:
    public class FutureTask<V> implements RunnableFuture<V> {}
    public interface RunnableFuture extends Runnable, Future<V> {}

Change-Id: I0cd66a655fbe7fd5c7c48099d656b7a39368dac4