alloc.c problem when GC_MARK_STACK is GC_USE_GCPROS_AS_BEFORE

[Barry Fishman]

Building the CVS head on a adm64 running SuSE Linux 9.1, linking fails
with missing function mark_maybe_object().

This is due to a problem in alloc.c.  The static function
mark_maybe_object() is not defined when GC_MARK_STACK is zero but
is still used in mark_object() for 'case Lisp_Misc_Save_Value:'.

I don't understand the code well enough to suggest a patch.

-- 
Barry Fishman