fix geometry usage against new variant

include/mapnik/feature.hpp

@@ -105,7 +105,7 @@ public:
         : id_(_id),
         ctx_(ctx),
         data_(ctx_->mapping_.size()),
-        geom_(geometry::geometry_empty()),
+        geom_(),
         raster_() {}
 
     inline mapnik::value_integer id() const { return id_;}

src/renderer_common/render_group_symbolizer.cpp

@@ -119,7 +119,7 @@ void render_group_symbolizer(group_symbolizer const& sym,
         // symbolizers with avoid-edges set: only the avoid-edges of
         // the group symbolizer itself should matter.
         geometry::point<double> origin_pt(x,y);
-        sub_feature->set_geometry(origin_pt);
+        sub_feature->set_geometry(std::move(origin_pt));
         // get the layout for this set of properties
         for (auto const& rule : props->get_rules())
         {