bugfixes; add NullPointerException.java

classpath/java/lang/NullPointerException.java

@@ -0,0 +1,19 @@
+package java.lang;
+
+public class NullPointerException extends RuntimeException {
+  public NullPointerException(String message, Throwable cause) {
+    super(message, cause);
+  }
+
+  public NullPointerException(String message) {
+    this(message, null);
+  }
+
+  public NullPointerException(Throwable cause) {
+    this(null, cause);
+  }
+
+  public NullPointerException() {
+    this(null, null);
+  }
+}