[InterNetNews/inn] 05f05e: Add clientlib variables as extern in libinn

[Julien ÉLIE]

  Branch: refs/heads/main
  Home:   https://github.com/InterNetNews/inn
  Commit: 05f05e653beb6e320f20a19dc24719788ab40850
      https://github.com/InterNetNews/inn/commit/05f05e653beb6e320f20a19dc24719788ab40850
  Author: Julien ÉLIE <Julien-Elie at users.noreply.github.com>
  Date:   2021-12-11 (Sat, 11 Dec 2021)

  Changed paths:
    M include/inn/libinn.h
    M lib/clientlib.c

  Log Message:
  -----------
  Add clientlib variables as extern in libinn

Fix previous commit e7f9404ad505e4c38d6eb196e66bfc3b77f040c2 where
extern variables were initialized at the same time of their declaration.
Add them to libinn.h, marked as extern.