[PATCH] pthread_once hangs when init routine throws an exception [BZ #18435]

[Martin Sebor]

> this broke
>
> nptl/tst-join5
> nptl/tst-once3
>
> tests on aarch64.
>
> the cleanup handler of the pthread_once and pthread_join
> implementation don't run when they are canceled.

I'll look into it as soon as I get access to an aarch64 machine.

Martin