gplugin/gplugin

7027845d098d
Make sure gtk4 was found before trying to build vala bindings against it

This error only showed up when gtk4 was enabled but not found.

Testing Done:
Built on haiku that doesn't have gtk without setting `-Dgtk4=false`.
Built on debian testing normally.

Reviewed at https://reviews.imfreedom.org/r/3069/
/*
* Copyright (C) 2011-2020 Gary Kramlich <grim@reaperworld.com>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, see <https://www.gnu.org/licenses/>.
*/
#if !defined(GPLUGIN_GLOBAL_HEADER_INSIDE) && !defined(GPLUGIN_COMPILATION)
#error "only <gplugin.h> may be included directly"
#endif
#ifndef GPLUGIN_OPTIONS_H
#define GPLUGIN_OPTIONS_H
#include <glib.h>
#include <gplugin/gplugin-version.h>
G_BEGIN_DECLS
GPLUGIN_AVAILABLE_IN_ALL
GOptionGroup *gplugin_get_option_group(void);
G_END_DECLS
#endif /* GPLUGIN_OPTIONS_H */