posix_openpt vs getpt??

[Florian Weimer]

* Samuel Thibault:

> In sysdeps/unix/bsd/getpt.c we can read:
>
> /* We cannot define posix_openpt in general for BSD systems.  */
>
> I do not see why posix_openpt can't be defined like getpt is. Is there
> a semantic difference between them beyond the open flags that could be
> just passed to the open() call?  Notably, Linux' getpt() is actually
> implemented as __posix_openpt (O_RDWR)...

We don't have an in-tree BSD port, and the BSD at the time was
probably quite different from what we have today.  I suggest to ignore
the comment and rearrange things in the way that make the most sense
for Linux and Hurd.