xdg: chase swaywm/wlroots@9e58301df7f0

xdg: chase swaywm/wlroots@9e58301df7f0

src/xdg.c:269:48: error: no member named 'subsurfaces' in 'struct wlr_surface'
                wl_list_for_each(subsurface, &view->surface->subsurfaces,
                                              ~~~~~~~~~~~~~  ^
/usr/include/wayland-util.h:443:30: note: expanded from macro 'wl_list_for_each'
        for (pos = wl_container_of((head)->next, pos, member);  \
                                    ^~~~
/usr/include/wayland-util.h:409:32: note: expanded from macro 'wl_container_of'
        (__typeof__(sample))((char *)(ptr) -                            \
                                      ^~~

Based on https://github.com/swaywm/sway/commit/3162766eef14