WIP/RFC patch for Linux termios overhaul

[Florian Weimer]

* H. Peter Anvin:

> On March 26, 2025 10:19:27 AM PDT, Florian Weimer <fweimer@redhat.com> wrote:
>>* H. Peter Anvin:
>>
>>> It is not even tested, never mind productized, but I would love to get
>>> some feedback on this approach and implementation.
>>>
>>> https://git.zytor.com/linux/glibc.git/commit/?h=hpa/termios
>>
>>I think it's better to remove <termio.h> stuff from
>>sysdeps/unix/sysv/linux/bits/ioctl-types.h because it's not really
>>usable if applications include <termios.h> and <sys/ioctl.h>.
>>
>>I don't know if we need to keep <termio.h> working, pratically speaking.
>>Removing <termio.h> and the bad ioctl parts without prior deprecation
>>warning might be considered a bit rude, but perhaps no one will notice.
>>We could put the removal into Fedora rawhide if it's separate from the
>>rest (the new symbol additions).

> ... which pretty much means doing something like what I have been
> doing here, and then removing termio.h.

Well, we can't really add the other (functional) changes before those
land in the upstream branch.  That would be a bit of a fork. 8-)

So if we want to do this experiment, we would have to sequence the
<termio.h> removal patch first.

Thanks,
Florian