Remove unused zend_shutdown_constants() (#13657)

The zend_shutdown_constants() usage was removed in
21698c1 (memory leak)
and in b80cb7b (unicode support).

Author: petk

Zend/zend_constants.c

@@ -116,13 +116,6 @@ void zend_register_standard_constants(void)
 	null_const = zend_hash_str_find_ptr(EG(zend_constants), "NULL", sizeof("NULL")-1);
 }
 
-
-void zend_shutdown_constants(void)
-{
-	zend_hash_destroy(EG(zend_constants));
-	free(EG(zend_constants));
-}
-
 ZEND_API void zend_register_null_constant(const char *name, size_t name_len, int flags, int module_number)
 {
 	zend_constant c;

Zend/zend_constants.h

@@ -71,7 +71,6 @@ BEGIN_EXTERN_C()
 void clean_module_constants(int module_number);
 void free_zend_constant(zval *zv);
 void zend_startup_constants(void);
-void zend_shutdown_constants(void);
 void zend_register_standard_constants(void);
 ZEND_API bool zend_verify_const_access(zend_class_constant *c, zend_class_entry *ce);
 ZEND_API zval *zend_get_constant(zend_string *name);