Regarding the ULTRIX and OSF1 compats

[Maxime Villard <max%m00nbsd.net@localhost>]

New thread, CC'ed to port-pmax@ and port-alpha@, in the continuity of:

	https://mail-index.netbsd.org/tech-kern/2019/03/09/msg024754.html

Basically, there were talks about retiring COMPAT_ULTRIX and COMPAT_OSF1,
because they are of questionable utility, in addition to being clear dead
wood; as I said, limited use case, no maintenance done in these areas,
inability to test changes, and the list goes on.

So, does anyone have anything to say about that?