fix a couple of ByteBuffer regressions

The compact() and put(ByteBuffer) methods regressed as of the recent
refactoring to support direct byte buffers.

classpath/java/nio/ArrayByteBuffer.java

@@ -31,6 +31,10 @@ class ArrayByteBuffer extends ByteBuffer {
     return b;
   }
 
+  public boolean hasArray() {
+    return true;
+  }
+
   public byte[] array() {
     return array;
   }
@@ -49,9 +53,10 @@ class ArrayByteBuffer extends ByteBuffer {
   }
 
   public ByteBuffer put(ByteBuffer src) {
-    checkPut(position, src.remaining());
+    int length = src.remaining();
-    src.get(array, arrayOffset + position, src.remaining());
+    checkPut(position, length);
-    position += src.remaining();
+    src.get(array, arrayOffset + position, length);
+    position += length;
     return this;
   }
 

classpath/java/nio/ByteBuffer.java

@@ -53,13 +53,15 @@ public abstract class ByteBuffer
   }
 
   public ByteBuffer compact() {
+    int remaining = remaining();
+
     if (position != 0) {
       ByteBuffer b = slice();
       position = 0;
       put(b);
     }
 
-    position = remaining();
+    position = remaining;
     limit(capacity());
     
     return this;