[PATCH glibc 1/1] support: implement xpthread key create/delete (v6)

[Florian Weimer]

* Mathieu Desnoyers via Libc-alpha:

> Expose xpthread_key_create () and xpthread_key_delete () wrappers
> for tests.
>
> Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
> CC: Carlos O'Donell <carlos@redhat.com>
> CC: Florian Weimer <fweimer@redhat.com>
> CC: Joseph Myers <joseph@codesourcery.com>
> CC: Szabolcs Nagy <szabolcs.nagy@arm.com>
> CC: libc-alpha@sourceware.org
> ---
> Changes since v1:
> - Update ChangeLog.
> - Wrap long line in xpthread_key_create.
>
> Changes since v2:
> - Rebase on glibc 2.30.
>
> Changes since v3:
> - Update copyright range to include 2020.
>
> Changes since v4:
> - Update copyright date to specifically only 2020.
> - Change xpthread_key_create prototype to return a pthread_key_t,
>   similarly to what has been done for xpthread_create.
>
> Changes since v5:
> - Use https:// rather than http://.

This version looks good to me (minus the Signed-off-by:).