sysctl: hide 2.x era compat node
r23081 introduced kern.dummy oid as a semi ABI compat for kern.maxsockbuf
that was moved to a new namespace. It never functioned as an alias of any
kind and was just returning 0 unconditionally, hence it was probably
provided to keep some 3rd party programmes happy about sysctl(3) not
reporting an error because of non-existing oid.
After nearly 23 years it seems reasonable to just hide it from sysctl(8)
list not to cause unnecessary confusion as for its purpose.
Reported by: Antranig Vartanian <firstname.lastname@example.org>
Reviewed by: kib (mentor)
Approved by: kib (mentor)
Differential Revision: https://reviews.freebsd.org/D22982