PATCH, libjava: silence more warnings

[Dave Korn]

Ben Elliston wrote:

>  ::java::lang::String *
> -java::net::VMURLConnection::guessContentTypeFromBuffer (jbyteArray bytes,
> -                                                       jint valid)
> +java::net::VMURLConnection::guessContentTypeFromBuffer (jbyteArray bytes __attribute__ ((unused)),
> +                                                       jint valid __attribute__ ((unused)))

  There's a #define MAYBE_UNUSED in include/jvm.h, as used in
java/lang/natClass.cc.  But maybe jvm.h isn't available here?

    cheers,
      DaveK