games/freeorion: unbreak with boost 1.68

In file included from GG/src/GUI.cpp:44:
GG/src/gilext/io/png_io.hpp:39:10: fatal error: 'boost/gil/extension/io/io_error.hpp' file not found
#include <boost/gil/extension/io/io_error.hpp>

^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

GG/src/gilext/io/png_io_private.hpp:46:37: error: use of undeclared identifier 'bits8'
template <> struct png_is_supported<bits8,gray_t> {BOOST_STATIC_CONSTANT(bool,value=true);};

^

In file included from GG/src/Texture.cpp:39:
GG/src/gilext/io/png_dynamic_io.hpp:37:10: fatal error: 'boost/gil/extension/io/dynamic_io.hpp' file not found
#include <boost/gil/extension/io/dynamic_io.hpp>

^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

In file included from GG/src/gilext/io/png_dynamic_io.hpp:43:
In file included from GG/src/gilext/io/png_io.hpp:38:
In file included from GG/src/gilext/io/png_io_private.hpp:30:
GG/src/gilext/io/../typedefs.hpp:30:40: error: too few arguments provided to function-like macro invocation
GIL_DEFINE_BASE_TYPEDEFS(8, gray_alpha)

^

/usr/local/include/boost/gil/typedefs.hpp:86:9: note: macro 'GIL_DEFINE_BASE_TYPEDEFS' defined here
#define GIL_DEFINE_BASE_TYPEDEFS(B, CM, CS) \

^

In file included from GG/src/GUI.cpp:44:
In file included from GG/src/gilext/io/png_io.hpp:40:
GG/src/gilext/io/png_io_private.hpp:167:27: error: expected class name
class png_reader : public file_mgr {

^

PR: 229699
Obtained from: upstream
Approved by: maintainer timeout (2 weeks)