[InterNetNews/inn] 5cc4e0: filechan: Remove it, use buffchan instead

[Julien ÉLIE]

  Branch: refs/heads/main
  Home:   https://github.com/InterNetNews/inn
  Commit: 5cc4e0d12ffb5bb2d5064534e1a13f8f34a8234c
      https://github.com/InterNetNews/inn/commit/5cc4e0d12ffb5bb2d5064534e1a13f8f34a8234c
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2021-11-20 (Sat, 20 Nov 2021)

  Changed paths:
    M .gitignore
    M MANIFEST
    M TODO
    M backends/Makefile
    M backends/buffchan.c
    R backends/filechan.c
    R backends/map.c
    R backends/map.h
    M doc/man/Makefile
    R doc/man/filechan.8
    M doc/pod/buffchan.pod
    M doc/pod/innupgrade.pod
    M doc/pod/news.pod
    M doc/pod/procbatch.pod
    M scripts/inncheck.in
    M scripts/innupgrade.in
    M support/mkmanifest
    M tests/data/upgrade/newsfeeds
    M tests/data/upgrade/newsfeeds.ok

  Log Message:
  -----------
  filechan: Remove it, use buffchan instead

Remove filechan in favour of buffchan.
Update innupgrade to take care of the change in newsfeeds.

Move map.c into buffchan.c as it is the only program still using these
functions.