fix ia64 longjmp() to work from alternate signal-stack

[Jakub Jelinek]

On Tue, Aug 31, 2004 at 09:14:20AM -0700, David Mosberger wrote:
> So you want me to create an ia64-specific version of __libc_longjmp()
> which will be sigaltstack-safe while everything else goes to
> the old longjmp implementation, right?
> 
> The only callers of __libc_longjmp() I found are:
> 
> ./linuxthreads/sysdeps/pthread/ptlongjmp.c:  __libc_longjmp (env, val);
> ./nptl/sysdeps/pthread/pt-longjmp.c:  __libc_longjmp (env, val);
> ./nptl/unwind.c:    __libc_longjmp ((struct __jmp_buf_tag *) buf->cancel_jmp_buf, 1);
> ./nptl/unwind.c:  __libc_longjmp ((struct __jmp_buf_tag *) ibuf->cancel_jmp_buf, 1);
> 
> so I think this would have the desired effect.

The first two should use the old longjmp implementation, the latter
two the sigaltstack-safe one.

	Jakub