examples/url2file.c: add missing curl_global_cleanup() call

Reported-by: XhstormR on github
Fixes #2245

docs/examples/url2file.c

@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2016, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
  *
  * This software is licensed as described in the file COPYING, which
  * you should have received as part of this distribution. The terms
@@ -80,5 +80,7 @@ int main(int argc, char *argv[])
   /* cleanup curl stuff */
   curl_easy_cleanup(curl_handle);
 
+  curl_global_cleanup();
+
   return 0;
 }