Fix checkstyle suppression

Author: msimacek

graalpython/com.oracle.graal.python/src/com/oracle/graal/python/util/IPAddressUtil.java

@@ -38,7 +38,7 @@
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  */
-// CHECKSTYLE:OFF
+// Checkstyle: stop
 package com.oracle.graal.python.util;
 
 import java.net.URL;