[build] Move gthr to toplevel libgcc

[John David Anglin]

On 8-Aug-11, at 12:29 PM, Rainer Orth wrote:

> John David Anglin <dave.anglin@nrc-cnrc.gc.ca> writes:
>
>>> I haven't moved two macros used in gthr*.h yet: GTHREAD_USE_WEAK and
>>> SUPPORTS_WEAK.  This seems to warrant a separate followup patch,  
>>> but for
>>> the record I report my findings:
>>>
>>> * GTHREAD_USE_WEAK must be defined explicitly.  It needs to be  
>>> poisoned
>>> in system.h after the move.  Right now, only a few targets defined a
>>> non-default value:
>>>
>>> darwin.h		#define GTHREAD_USE_WEAK 0
>>> i386/cygwin.h		#define GTHREAD_USE_WEAK 0
>>>
>>> ia64/hpux.h		#define GTHREAD_USE_WEAK 0
>>> pa/pa64-hpux.h	#define GTHREAD_USE_WEAK 0
>>> pa/som.h		#define GTHREAD_USE_WEAK 0
>>>
>>> The last 3 could be handled in a new hpux-lib.h, but perhaps this
>>> isn't necessary if ax_sys_weak_alias.m4 works.
>>
>> I'm not sure this is possible in general on HP-UX.
>
> Do you suggest that support for weak definitions (undefined weak)  
> cannot
> be detected by a configure test on HP-UX?

Undefined weak support can be detected with a simple link test.

The situation with aliases is more complex.

Dave