In `perl.h`, there is:
```
#ifdef I_LIBUTIL
#include
#endif
```
and on FreeBSD, `I_LIBUTIL` is defined in Perl's `config.h`. That header does
not really appear to be necessary for Perl, but it has the side effect of
declaring a `properties` type. This is a generic name used in our code base, so
we hack around it with the preprocessor. Preferably, FreeBSD would fix that in
their Perl port in the future.
/*
* 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 <http://www.gnu.org/licenses/>.
*/
/**
* SECTION:gplugin-version
* @Title: Version Information
* @Short_description: variables and functions to check the version of GPlugin.
*
* GPlugin provided version information, primarily useful when building against
* GPlugin. Applications will not typically use the features described here