Bug#47998: msgget IPC not implemented

[Roland McGrath]

It is certainly the case that sysv-style ipc and shared memory are not
implemented on the hurd, and are not likely to be implemented any time soon.
We don't know of any particularly desireable things that sysv ipc provides
that can't be done another way (unix-domain sockets, pipes, etc, even
without getting into hurd-specific ways).