Switching MK_ATM to no by default

From: Emmanuel Vadot <manu_at_bidouilliste.com>
Date: Fri, 27 Jan 2023 10:34:10 UTC
 Hello,

 It's 2023 and I don't think that ATM have any users (but could be
wrong hence the mail).
 Is everyone ok with switching MK_ATF to no by default ?
 This will stop installed sscop(1) and libngatm (Netgraph support).

 If no one complain I'll do that for 14-CURRENT mid-february.

 Cheers,

-- 
Emmanuel Vadot <manu@bidouilliste.com> <manu@freebsd.org>