[bytes] Simplify hash function

Part of https://github.com/harfbuzz/harfbuzz/issues/4227

src/hb-array.hh

@@ -458,21 +458,9 @@ inline uint32_t hb_array_t<const char>::hash () const
 {
   // FNV-1a hash function
   uint32_t current = /*cbf29ce4*/0x84222325;
-  unsigned i = 0;
-
-#if defined(__OPTIMIZE__) && !defined(HB_NO_PACKED) && \
-    ((defined(__GNUC__) && __GNUC__ >= 5) || defined(__clang__))
-  struct __attribute__((packed)) packed_uint32_t { uint32_t v; };
-  for (; i + 4 <= this->length; i += 4)
-  {
-    current = current ^ hb_hash ((uint32_t) ((const packed_uint32_t *) &this->arrayZ[i])->v);
-    current = current * 16777619;
-  }
-#endif
-
-  for (; i < this->length; i++)
+  for (auto &v : *this)
   {
-    current = current ^ hb_hash (this->arrayZ[i]);
+    current = current ^ v;
     current = current * 16777619;
   }
   return current;
@@ -483,21 +471,9 @@ inline uint32_t hb_array_t<const unsigned char>::hash () const
 {
   // FNV-1a hash function
   uint32_t current = /*cbf29ce4*/0x84222325;
-  unsigned i = 0;
-
-#if defined(__OPTIMIZE__) && !defined(HB_NO_PACKED) && \
-    ((defined(__GNUC__) && __GNUC__ >= 5) || defined(__clang__))
-  struct __attribute__((packed)) packed_uint32_t { uint32_t v; };
-  for (; i + 4 <= this->length; i += 4)
-  {
-    current = current ^ hb_hash ((uint32_t) ((const packed_uint32_t *) &this->arrayZ[i])->v);
-    current = current * 16777619;
-  }
-#endif
-
-  for (; i < this->length; i++)
+  for (auto &v : *this)
   {
-    current = current ^ hb_hash (this->arrayZ[i]);
+    current = current ^ v;
     current = current * 16777619;
   }
   return current;