Add a link from LruCache to the Android support package (compatibility library).

 * <p>This class does not allow null to be used as a key or value. A return

 * value of null from {@link #get}, {@link #put} or {@link #remove} is

 * unambiguous: the key was not in the cache.

 *

 * <p>This class appeared in Android 3.1 (Honeycomb MR1); it's available as part

 * of <a href="http://developer.android.com/sdk/compatibility-library.html">Android's

 * Support Package</a> for earlier releases.

 */

public class LruCache<K, V> {

    private final LinkedHashMap<K, V> map;