[PATCH] stdlib: Consolidate getentropy and adapt to POSIX 2024 semantics

[Florian Weimer]

* Cristian Rodríguez:

> Are we sure all this error handling is actually necessary or correct?
>  I know the manual pages are outdated and do not reflect the state of
> things post Jason massive RNG rework..
> But at least the previous implementation promised on reads <= 256 not
> to short read, always return at least that amount of bytes, so in
> theory returning 0 or EINTR is/was not possible with 0 flags.

Most Linux systems do not use the upstream random driver, but modified
versions of it.

Thanks,
Florian