x11-wm/dwl: unbreak on GCC architectures

In file included from dwl.c:377:
client.h: In function 'client_get_appid':
client.h:63: error: 'struct wlr_xdg_surface' has no member named 'toplevel'
client.h: In function 'client_get_title':
client.h:88: error: 'struct wlr_xdg_surface' has no member named 'toplevel'
dwl.c: In function 'createkeyboard':
dwl.c:797: error: 'struct wlr_input_device' has no member named 'keyboard'
dwl.c:800: error: 'struct wlr_input_device' has no member named 'keyboard'
dwl.c:803: error: 'struct wlr_input_device' has no member named 'keyboard'
dwl.c:804: error: 'struct wlr_input_device' has no member named 'keyboard'
dwl.c: In function 'createnotify':
dwl.c:901: error: 'struct wlr_xdg_surface' has no member named 'toplevel'
dwl.c:902: error: 'struct wlr_xdg_surface' has no member named 'toplevel'
dwl.c: In function 'keypress':
dwl.c:1242: error: 'struct wlr_input_device' has no member named 'keyboard'
dwl.c:1245: error: 'struct wlr_input_device' has no member named 'keyboard'
dwl.c: In function 'keypressmod':
dwl.c:1277: error: 'struct wlr_input_device' has no member named 'keyboard'