util/IMdkit: Fix the range of memset() in i18nIc.c

BUG=https://github.com/ibus/ibus/issues/1891

Review URL: https://codereview.appspot.com/320010043

util/IMdkit/i18nIc.c

@@ -478,7 +478,7 @@ static XICAttribute *CreateNestedList (CARD16 attr_id,
     if (nest_list->value == NULL)
         return NULL;
     /*endif*/
-    memset (nest_list->value, 0, sizeof (value_length));
+    memset (nest_list->value, 0, value_length);
 
     nest_list->attribute_id = attr_id;
     nest_list->value_length = value_length;