Use more compact representation for packed arrays.

- for packed arrays we store just an array of zvals without keys.
- the elements of packed array are accessible throuf as ht->arPacked[i]
  instead of ht->arData[i]
- in addition to general ZEND_HASH_FOREACH_* macros, we introduced similar
  familied for packed (ZEND_HASH_PACKED_FORECH_*) and real hashes
  (ZEND_HASH_MAP_FOREACH_*)
- introduced an additional family of macros to access elements of array
  (packed or real hashes) ZEND_ARRAY_ELEMET_SIZE, ZEND_ARRAY_ELEMET_EX,
  ZEND_ARRAY_ELEMET, ZEND_ARRAY_NEXT_ELEMENT, ZEND_ARRAY_PREV_ELEMENT
- zend_hash_minmax() prototype was changed to compare only values

Because of smaller data set, this patch may show performance improvement
on some apps and benchmarks that use packed arrays. (~1% on PHP-Parser)

TODO:
    - sapi/phpdbg needs special support for packed arrays (WATCH_ON_BUCKET).
    - zend_hash_sort_ex() may require converting packed arrays to hash.

ext/mysqlnd/mysqlnd_debug.c

@@ -430,7 +430,7 @@ MYSQLND_METHOD(mysqlnd_debug, close)(MYSQLND_DEBUG * self)
 
 			self->m->log_va(self, __LINE__, __FILE__, 0, "info : ",
 					"number of functions: %d", zend_hash_num_elements(&self->function_profiles));
-			ZEND_HASH_FOREACH_STR_KEY_PTR(&self->function_profiles, string_key, f_profile) {
+			ZEND_HASH_MAP_FOREACH_STR_KEY_PTR(&self->function_profiles, string_key, f_profile) {
 				self->m->log_va(self, __LINE__, __FILE__, -1, "info : ",
 						"%-40s\tcalls=%5" PRIu64
 						"  own_slow=%5" PRIu64