PATCH: Add x32 support to <sys/user.h>

[Roland McGrath]

>    struct user_regs_struct*	u_ar0;
> +# ifdef __ILP32__
> +  unsigned int			pad0;
> +# endif
>    struct user_fpregs_struct*	u_fpstate;
> -  unsigned long int		magic;
> +# ifdef __ILP32__
> +  unsigned int			pad1;
> +# endif
> +  __extension__ unsigned long long int	magic;

For consistency all fields should have names starting with "u_".
But I prefer the union trick over #ifdef'd padding fields.