math/saga: Update to 8.4.1

Fixes serveral tools, most noteworthy for FreeBSD users in Visibilty Analysis,
pj_proj4/crs_transform, io_gdal/gdal_driver, saga_gui/data_source_pgsql,
saga_api/projections, saga_api/CSG_Colors, Split Lines with Lines, and
saga_gdi/3d_view_canvas

Changelog: https://sourceforge.net/p/saga-gis/wiki/Changelog%208.4.1/attachment/changelog_saga_8.4.1.txt