Cross linking dynamic executables

[Andrew STUBBS]

> I recommend you try --with-sysroot, which should change where 
> we search
> for the dynamic linker.

That doesn't do what I require. At least not quite. Not without changing
where I keep things anyway.

However, if you feel that my patch is not suitable then that's fine. I can
always use it locally (till I find a better way). I didn't really expect
this one to go anywhere. It's just something I've found useful.

Thanks

Andrew