pidgin/purple-plugin-pack

Use the meson summary instead of manually building our summary with message

Testing Done:
Ran `ninja reconfigure` and verified the output.

```
purple-plugin-pack 2.8.1dev

libpurple
install directory: /usr/local/lib/purple-2
data directory : /usr/local/share
plugins : autoreply, bash, capsnot, colorize, dewysiwygification, dice, eight_ball, flip,
google, groupmsg, highlight, ignore, irc-more, irchelper, listhandler, ning,
oldlogger, omegle, showoffline, simfix, slashexec, snpp, splitter, sslinfo,
translate, xmppprio

pidgin
install directory: /usr/local/lib/pidgin
data directory : /usr/local/share
plugins : album, blistops, convbadger, difftopic, enhancedhist, gRIM, icon-override, irssi,
lastseen, listlog, mystatusbox, nicksaid, plonkers, schedule, sepandtab,
switchspell, timelog

finch
install directory: /usr/local/lib
data directory : /usr/local/share
plugins :

User defined options
backend : ninja
```

Reviewed at https://reviews.imfreedom.org/r/2408/
/*
* irssi - Implements several irssi features for Purple
* Copyright (C) 2005-2008 Gary Kramlich <grim@reaperworld.com>
* Copyright (C) 2006-2008 John Bailey <rekkanoryo@rekkanoryo.org>
* Copyright (C) 2006-2008 Sadrul Habib Chowdhury <sadrul@users.sourceforge.net>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02111-1301, USA.
*/
#define PLUGIN_ID "gtk-plugin_pack-irssi"
#define PLUGIN_STATIC_NAME "irssi"
#define PLUGIN_AUTHOR "\n" \
"\tGary Kramlich <grim@reaperworld.com>\n" \
"\tJohn Bailey <rekkanoryo@rekkanoryo.org>\n" \
"\tSadrul Habib Chowdhury <sadrul@users.sourceforge.net>"
#define PREFS_ROOT_PARENT "/pidgin/plugins"
#define PREFS_ROOT "/pidgin/plugins/" PLUGIN_ID
#define TEXTFMT_PREF PREFS_ROOT "/textfmt"
#define DATECHANGE_PREF PREFS_ROOT "/datechange"
#include "datechange.h"
#include "lastlog.h"
#include "layout.h"
#include "textfmt.h"
#include "window.h"