Remove stray line causing a compile error on Java 5

src/com/google/bitcoin/core/Utils.java

@@ -288,7 +288,6 @@ public class Utils {
     public static byte[] copyOf(byte[] in, int length) {
         byte[] out = new byte[length];
         System.arraycopy(in, 0, out, 0, Math.min(length, in.length));
-        Arrays.copyOf(in, 6);
         return out;
     }
 }