disable java on x86-darwin

[Andreas Tobler]

Geoffrey Keating wrote:

> Andreas' recent patch enabled Java on powerpc-darwin, which was good,
> but also on x86-darwin, which isn't good because libffi hasn't been
> ported to it yet so the build fails.  This disables it for x86-darwin.
> 
> Tested by building a cross to i386-darwin from powerpc-darwin (with
> several other patches to follow), and by configuring a native on
> powerpc-darwin.
> 
Well, I was a bit direct here.
If you (or anyone else) intend to do a libffi port for x86-darwin, I 
have a patch in testing for powerpc-darwin libffi and structure support, 
especially for closures.
Just in case, to reduce bug hunting work. And reduce double effort.

I'll post it as soon as I got a review on my testcases I wrote for.

Regards,
Andreas