6903753: (se) Selector should implement Closeable

Reviewed-by: chegar, forax

src/share/classes/java/nio/channels/Selector.java

@@ -25,6 +25,7 @@
 
 package java.nio.channels;
 
+import java.io.Closeable;
 import java.io.IOException;
 import java.nio.channels.spi.SelectorProvider;
 import java.util.Set;
@@ -202,7 +203,7 @@ import java.util.Set;
  * @see SelectionKey
  */
 
-public abstract class Selector {
+public abstract class Selector implements Closeable {
 
     /**
      * Initializes a new instance of this class.