Update test for AutoCloseIterator (#82)

avaje-jex/src/test/java/io/avaje/jex/jdk/AutoCloseIterator.java

@@ -5,7 +5,7 @@
 public class AutoCloseIterator<E> implements Iterator<E>, AutoCloseable {
 
   private final Iterator<E> it;
-  private boolean closed;
+  private volatile boolean closed;
 
   public AutoCloseIterator(Iterator<E> it) {
     this.it = it;