Revert "ftplistparser: keep state between invokes"

This reverts commit 8fb78f9ddc.

Unfortunately this fix introduces memory leaks I've not been able to fix
in several days. Reverting this for now to get the leaks fixed.

lib/ftplistparser.c

@@ -5,7 +5,7 @@
  *                            | (__| |_| |  _ <| |___
  *                             \___|\___/|_| \_\_____|
  *
- * Copyright (C) 1998 - 2018, Daniel Stenberg, <daniel@haxx.se>, et al.
+ * Copyright (C) 1998 - 2017, 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
@@ -1003,7 +1003,6 @@ size_t Curl_ftp_parselist(char *buffer, size_t size, size_t nmemb,
 
     i++;
   }
-  return retsize;
 
 fail: