Remove hb_success_t

Was not rolled-out yet.  So just expand.

src/hb-open-type.hh

@@ -632,7 +632,7 @@ struct ArrayOf
   void qsort (unsigned int start = 0, unsigned int end = (unsigned int) -1)
   { as_array ().qsort (start, end); }
 
-  hb_success_t serialize (hb_serialize_context_t *c, unsigned items_len)
+  HB_NODISCARD bool serialize (hb_serialize_context_t *c, unsigned items_len)
   {
     TRACE_SERIALIZE (this);
     if (unlikely (!c->extend_min (*this))) return_trace (false);
@@ -642,7 +642,7 @@ struct ArrayOf
   }
   template <typename Iterator,
 	    hb_requires (hb_is_source_of (Iterator, Type))>
-  hb_success_t serialize (hb_serialize_context_t *c, Iterator items)
+  HB_NODISCARD bool serialize (hb_serialize_context_t *c, Iterator items)
   {
     TRACE_SERIALIZE (this);
     unsigned count = items.len ();

src/hb.hh

@@ -338,7 +338,6 @@ extern "C" void  hb_free_impl(void *ptr);
 #else
 #  define HB_NODISCARD
 #endif
-#define hb_success_t HB_NODISCARD bool
 
 /* https://github.com/harfbuzz/harfbuzz/issues/1852 */
 #if defined(__clang__) && !(defined(_AIX) && (defined(__IBMCPP__) || defined(__ibmxl__)))