GNU libobjc on Darwin

[Stan Shebs]

Bill Northcott wrote:

> I may have mentioned this here before or perhaps it only went to 
> Andrew Pinski.
>
> Andrew has proposed some changes that allow GNU libobjc to build on 
> Darwin as libobjc-gnu.   These work for an FSF style build.
>
> However, on the apple-ppc-darwin branch the same patches don't build 
> the library.
> The cause is an APPLE_LOCAL mod to config/rs6000/darwin.h which 
> redefines ADJUST_FIELD_ALIGN to need three arguments.  This breaks in 
> encoding.c around line 838.  The only other place the macro appears to 
> be used is stor-layout.c.
>
> I can't make up my mind if this is an Apple bug or an FSF one.

I kind of volunteered to figure this one out at some point. We use
the extra argument to behave differently for the first field of a
structure, but it's not so clear whether it's critical or just a
leftover from old days.

Stan