[PATCH v2] Revert __HAVE_64B_ATOMICS configure check

[Maciej W. Rozycki]

Hi Wilco,

> > AFAICT in the __HAVE_64B_ATOMICS == 1 case `sem_t' includes a `uint64_t'
> > member, so the structure will have 64-bit alignment on the MIPS target.
> 
> sysdeps/mips/nptl/bits/semaphore.h has:
> 
> typedef union
> {
>   char __size[__SIZEOF_SEM_T];
>   long int __align;
> } sem_t;
> 
> Even if __SIZEOF_SEM_T is like the 64-bit ABI, the alignment will be 4 and
> so it can't use 64-bit atomics on this structure.

 Ah right, I looked at `struct new_sem' instead.  Oh well, you are right.  
Damn, who'd ever come up with that?  We'd have to bump up the ABI to get 
this to work with n32.

  Maciej