default postgresql version: why is it 16?

[Greg Troxel <gdt%lexort.com@localhost>]

tl;dr: Obviously not for changing in freeze, but why is the default 16
instead of 18?  Let's switch to 18. 


I find that I have a mix of versions on various machines.  Some 14, some
18.  This is a bit of a personal mess, not a pkgsrc problem.

However, in my bob builds, I end up with postgresql16, which I don't run
anywhere.  This is because the default version is 16, and when building
in bob (as opposed to pkg_rr or just make package), the builds start off
with empty chroots, and thus the "default is the installed version"
logic doesn't happen.

I wonder if 16 is intentional, but I see it was set almost two years ago
(surely the right choice then).

Upstream surely recommends 18 -- that's what release means -- but
probably there are pgsql-using packages that don't cope with 18.

Dusting off an old script, I find that in the 2026Q2 NetBSD 10 binary
package set, there are two packages that only build with 14 (which is
not 16!), and everything else seems to be ok with all of 14-18:

  MISSING 15 postgresql15-pgroonga
  MISSING 15 postgresql15-redislog

I therefore propose that post branch, we flip from 16 to 18.