Add HB_NO_OPTIONS

Part of https://github.com/harfbuzz/harfbuzz/issues/1652

src/hb-debug.hh

@@ -63,6 +63,9 @@ extern HB_INTERNAL hb_atomic_int_t _hb_options;
 static inline hb_options_t
 hb_options ()
 {
+#if defined(HB_NO_OPTIONS)
+  return hb_options_t ();
+#endif
   /* Make a local copy, so we can access bitfield threadsafely. */
   hb_options_union_t u;
   u.i = _hb_options.get_relaxed ();