[skip-ci] Fix comments and UPGRADING.INTERNALS for zend_type changes

UPGRADING.INTERNALS

@@ -8,6 +8,7 @@ PHP 8.1 INTERNALS UPGRADE NOTES
   e. ZEND_ATOL() changes
   f. Non-serializable classes should use ZEND_ACC_NOT_SERIALIZABLE
   g. _zend_hash_find_known_hash renamed to zend_hash_find_known_hash
+  h. Renaming of ZEND_TYPE_HAS_CLASS() into ZEND_TYPE_IS_COMPLEX()
 
 2. Build system changes
   a. New compiler flags
@@ -53,6 +54,9 @@ PHP 8.1 INTERNALS UPGRADE NOTES
      ZEND_ACC_NOT_SERIALIZABLE (@not-serializable in stubs) rather than the
      zend_class_(un)serialize_deny handlers which are removed.
   g. _zend_hash_find_known_hash has been renamed to zend_hash_find_known_hash.
+  h. ZEND_TYPE_HAS_CLASS() has been renamed to ZEND_TYPE_IS_COMPLEX() for clarity.
+     A zend_type element can contain a zend_type_list which might be either a union or an intersection,
+     or a single class stored as either a zend_string* or a zend_class_entry*.
 
 ========================
 2. Build system changes

Zend/zend_types.h

@@ -110,9 +110,11 @@ typedef void (*copy_ctor_func_t)(zval *pElement);
  *
  * ZEND_TYPE_IS_SET()        - checks if there is a type-hint
  * ZEND_TYPE_IS_ONLY_MASK()  - checks if type-hint refer to standard type only
- * ZEND_TYPE_HAS_CLASS()     - checks if type-hint contains some class
+ * ZEND_TYPE_IS_COMPLEX()    - checks if type is a type_list, or contains a class either as a CE or as a name
  * ZEND_TYPE_HAS_CE()        - checks if type-hint contains some class as zend_class_entry *
  * ZEND_TYPE_HAS_NAME()      - checks if type-hint contains some class as zend_string *
+ * ZEND_TYPE_IS_INTERSECTION() - checks if the type_list represents an intersection type list
+ * ZEND_TYPE_IS_UNION()      - checks if the type_list represents a union type list
  *
  * ZEND_TYPE_NAME()       - returns referenced class name
  * ZEND_TYPE_CE()         - returns referenced class entry