Declare asctime_r, ctime_r, gmtime_r, localtime_r for C2X

[Florian Weimer]

* Joseph Myers:

> C2X adds the asctime_r, ctime_r, gmtime_r and localtime_r functions.
> This patch duly adds __GLIBC_USE (ISOC2X) to the conditions under
> which <time.h> declares them.
>
> Tested for x86_64.
>
> diff --git a/time/time.h b/time/time.h
> index 7daaacce16..05d9098c13 100644
> --- a/time/time.h
> +++ b/time/time.h
> @@ -122,7 +122,7 @@ extern struct tm *gmtime (const time_t *__timer) __THROW;
>     of *TIMER in the local timezone.  */
>  extern struct tm *localtime (const time_t *__timer) __THROW;
>  
> -#ifdef __USE_POSIX
> +#if defined __USE_POSIX || __GLIBC_USE (ISOC2X)
>  /* Return the `struct tm' representation of *TIMER in UTC,
>     using *TP to store the result.  */
>  extern struct tm *gmtime_r (const time_t *__restrict __timer,
> @@ -132,7 +132,7 @@ extern struct tm *gmtime_r (const time_t *__restrict __timer,
>     using *TP to store the result.  */
>  extern struct tm *localtime_r (const time_t *__restrict __timer,
>  			       struct tm *__restrict __tp) __THROW;
> -#endif	/* POSIX */
> +#endif	/* POSIX || C2X */
>  
>  /* Return a string of the form "Day Mon dd hh:mm:ss yyyy\n"
>     that is the representation of TP in this format.  */
> @@ -141,7 +141,7 @@ extern char *asctime (const struct tm *__tp) __THROW;
>  /* Equivalent to `asctime (localtime (timer))'.  */
>  extern char *ctime (const time_t *__timer) __THROW;
>  
> -#ifdef __USE_POSIX
> +#if defined __USE_POSIX || __GLIBC_USE (ISOC2X)
>  /* Reentrant versions of the above functions.  */
>  
>  /* Return in BUF a string of the form "Day Mon dd hh:mm:ss yyyy\n"
> @@ -152,7 +152,7 @@ extern char *asctime_r (const struct tm *__restrict __tp,
>  /* Equivalent to `asctime_r (localtime_r (timer, *TMP*), buf)'.  */
>  extern char *ctime_r (const time_t *__restrict __timer,
>  		      char *__restrict __buf) __THROW;
> -#endif	/* POSIX */
> +#endif	/* POSIX || C2X */
>  
>  
>  /* Defined in localtime.c.  */

This patch is okay.  Thanks.

Note that this is the kind of patch where a patch review tool actually
helps because the context in the patch as posted is insufficient for
review.

Florian