[build] Move MD_UNWIND_SUPPORT to toplevel libgcc

[Kai Tietz]

2011/6/1 Richard Henderson <rth@redhat.com>:
> On 06/01/2011 09:01 AM, Rainer Orth wrote:
>> The problem with this approach is that some of the macros tested only
>> live in gcc, not libgcc once the libgcc sources no longer include tm.h
>> etc.  E.g. look at i386/mingw32.h:
>>
>> #if !TARGET_64BIT_DEFAULT && !defined (TARGET_BI_ARCH)
>> #define MD_UNWIND_SUPPORT "config/i386/w32-unwind.h"
>> #endif
>>
>> Both TARGET_64BIT_DEFAULT and TARGET_BI_ARCH live in gcc only, so at
>> least in the medium term, we need different tests here.
>
> For this specific case, surely neither isn't relevant.
> Surely the proper test, in the target header, is simply
>
> #ifndef __MINGW64__
>
> as one would write in normal user-level code.
>
>
> r~

Yes, thanks.  Well, we would loose here the ability to build for
mingw-w64 dw2 support for 32-bit (to be compatible to mingw.org's
32-bit variant, as they want to use this dw2 unwinder), but mingw-w64
doesn't want dw2-unwind in general, as dw2-unwind has some issues
about throwing of VC generated code. So this test might be ok too.

Regards,
Kai