xwm: Reduce window property debug output

We just print properties when they change now instead of dumping all
properties whenever we re-read them.  Also, make the property output a
little more concise.
diff --git a/src/xwayland/xwayland.h b/src/xwayland/xwayland.h
index 72a25cc..26be7de 100644
--- a/src/xwayland/xwayland.h
+++ b/src/xwayland/xwayland.h
@@ -122,6 +122,9 @@
 void
 dump_property(struct weston_wm *wm, xcb_atom_t property,
 	      xcb_get_property_reply_t *reply);
+void
+read_and_dump_property(struct weston_wm *wm,
+		       xcb_window_t window, xcb_atom_t property);
 
 const char *
 get_atom_name(xcb_connection_t *c, xcb_atom_t atom);