Make fetch_* OO same as func

Clsoses GH-6580.

Author: kamil-tekiela

ext/mysqli/mysqli.stub.php

@@ -355,19 +355,19 @@ public function fetch_all(int $mode = MYSQLI_NUM) {}
     public function fetch_array(int $mode = MYSQLI_BOTH) {}
 
     /**
-     * @return array|null
+     * @return array|null|false
      * @alias mysqli_fetch_assoc
      */
     public function fetch_assoc() {}
 
     /**
-     * @return object|null
+     * @return object|null|false
      * @alias mysqli_fetch_object
      */
     public function fetch_object(string $class = "stdClass", array $constructor_args = []) {}
 
     /**
-     * @return array|null
+     * @return array|null|false
      * @alias mysqli_fetch_row
      */
     public function fetch_row() {}

ext/mysqli/mysqli_arginfo.h

@@ -1,5 +1,5 @@
 /* This is a generated file, edit the .stub.php file instead.
- * Stub hash: 0403f612783ee03ff4f586f136b5d3481ecd072c */
+ * Stub hash: 5a8b778eaa9efcca7d3ad8bfdbaa31d9d07b25e8 */
 
 ZEND_BEGIN_ARG_WITH_RETURN_TYPE_MASK_EX(arginfo_mysqli_affected_rows, 0, 1, MAY_BE_LONG|MAY_BE_STRING)
 	ZEND_ARG_OBJ_INFO(0, mysql, mysqli, 0)