Remove usage of surface->sx|sy

These coordinates contain the all-time accumulated buffer attach point,
which is a way to perform incremental client-side initiated movement of
windows, intended as a way to maintain logical window positioning while
compensating for layout changes such as folding in a left side panel.

This value is not useful for implementing this feature, and break things
if they ever become non-zero. Their inclusion in calculations also tend
to cause confusion.

Remove usage of these coordinates, removing the ability for clients to
move themselves. This may again be supported if a better API is made
available from wlroots.

sway/desktop/output.c

@@ -99,8 +99,8 @@ static bool get_surface_box(struct surface_iterator_data *data,
 	int sw = surface->current.width;
 	int sh = surface->current.height;
 
-	double _sx = sx + surface->sx;
+	double _sx = sx;
-	double _sy = sy + surface->sy;
+	double _sy = sy;
 	rotate_child_position(&_sx, &_sy, sw, sh, data->width, data->height,
 		data->rotation);
 

sway/desktop/render.c

@@ -159,8 +159,8 @@ static void render_surface_iterator(struct sway_output *output, struct sway_view
 	struct wlr_box dst_box = *_box;
 	struct sway_container *container = data->container;
 	if (container != NULL) {
-		dst_box.width = fmin(dst_box.width, container->current.content_width - surface->sx);
+		dst_box.width = fmin(dst_box.width, container->current.content_width);
-		dst_box.height = fmin(dst_box.height, container->current.content_height - surface->sy);
+		dst_box.height = fmin(dst_box.height, container->current.content_height);
 	}
 	scale_box(&dst_box, wlr_output->scale);