[PATCH] Document pthread_[gs]etattr_default_np in the manual

[Roland McGrath]

> Get the default attribute values and set @var{attr} to match.  This
> function returns @math{0} on success and a non-zero error code on
> failure.

That's fine.

> Do you want me to additionally mention that there are currently no
> failure codes defined?

I think just failing to mention any is fine.

> +The @glibcadj{} provides non-standard API functions to set and get the default

@Theglibc{}