[InterNetNews/inn] f26623: Fix inclusion of <sys/select.h>

[Julien ÉLIE]

  Branch: refs/heads/main
  Home:   https://github.com/InterNetNews/inn
  Commit: f2662303b8b473beb819b956b006f19fed9018c0
      https://github.com/InterNetNews/inn/commit/f2662303b8b473beb819b956b006f19fed9018c0
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2023-07-08 (Sat, 08 Jul 2023)

  Changed paths:
    M innd/innd.c
    M lib/nntp.c
    M nnrpd/auth-ext.c
    M nnrpd/misc.c
    M nnrpd/nnrpd.c
    M nnrpd/perm.c

  Log Message:
  -----------
  Fix inclusion of <sys/select.h>

It was sometimes missing, and sometimes useless.