remove GNU Classpath and Apache Harmony compatibility code

Rather than try to support mixing Avian's core classes with those of
an external class library -- which necessitates adding a lot of stub
methods which throw UnsupportedOperationExceptions, among other
comprimises -- we're looking to support such external class libraries
in their unmodified forms.  The latter strategy has already proven
successful with OpenJDK's class library.  Thus, this commit removes
the stub methods, etc., which not only cleans up the code but avoids
misleading application developers as to what classes and methods
Avian's built-in class library supports.

classpath/java/lang/Thread.java

@@ -24,11 +24,8 @@ public class Thread implements Runnable {
   private Object sleepLock;
   private ClassLoader classLoader;
   private UncaughtExceptionHandler exceptionHandler;
-
-  // package private for GNU Classpath, which inexplicably bypasses
-  // the accessor methods:
-  String name;
-  ThreadGroup group;
+  private String name;
+  private ThreadGroup group;
 
   private static UncaughtExceptionHandler defaultExceptionHandler;
 
@@ -287,22 +284,6 @@ public class Thread implements Runnable {
     return peer;
   }
 
-  public void stop() {
-    throw new UnsupportedOperationException();
-  }
-
-  public void stop(Throwable t) {
-    throw new UnsupportedOperationException();
-  }
-
-  public void suspend() {
-    throw new UnsupportedOperationException();
-  }
-
-  public void resume() {
-    throw new UnsupportedOperationException();
-  }
-
   public interface UncaughtExceptionHandler {
     public void uncaughtException(Thread t, Throwable e);
   }