PATCH: use gcc_assert, gcc_unreachable in java frontend

[Ben Elliston]

> >Tested on powerpc-linux with a full bootstrap and no regressions when
> >running make check-target-libjava run.  Okay for the trunk?
> 
> Disable-checking.....

Argh :-/

> 2006-02-04  Andreas Tobler  <a.tobler@schweiz.ch>
>
> 	* expr.c (java_stack_swap): Revert gcc_assert patch

I can't approve it, but since it reverts my change, then I think
that's OK.  Thanks,

Ben