Fix casing of NULL default values

Author: kocsismate

ext/ldap/ldap.stub.php

@@ -790,12 +790,12 @@ function ldap_8859_to_t61(string $value): string|false {}
      * @param string $response_data
      * @param string $response_oid
      */
-    function ldap_exop(LDAP\Connection $ldap, string $request_oid, ?string $request_data = null, ?array $controls = NULL, &$response_data = UNKNOWN, &$response_oid = null): LDAP\Result|bool {}
+    function ldap_exop(LDAP\Connection $ldap, string $request_oid, ?string $request_data = null, ?array $controls = null, &$response_data = UNKNOWN, &$response_oid = null): LDAP\Result|bool {}
     /**
      * @param string $response_data
      * @param string $response_oid
      */
-    function ldap_exop_sync(LDAP\Connection $ldap, string $request_oid, ?string $request_data = null, ?array $controls = NULL, &$response_data = null, &$response_oid = null): LDAP\Result|bool {}
+    function ldap_exop_sync(LDAP\Connection $ldap, string $request_oid, ?string $request_data = null, ?array $controls = null, &$response_data = null, &$response_oid = null): LDAP\Result|bool {}
     #endif
 
     #ifdef HAVE_LDAP_PASSWD