curl_formget.3: correct return code

Closes #375

docs/libcurl/curl_formget.3

@@ -5,7 +5,7 @@
 .\" *                            | (__| |_| |  _ <| |___
 .\" *                             \___|\___/|_| \_\_____|
 .\" *
-.\" * Copyright (C) 1998 - 2011, Daniel Stenberg, <daniel@haxx.se>, et al.
+.\" * Copyright (C) 1998 - 2015, 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
@@ -26,7 +26,7 @@ curl_formget - serialize a previously built multipart/formdata HTTP POST chain
 .nf
 .B #include <curl/curl.h>
 
-void curl_formget(struct curl_httppost * form, void *userp,
+int curl_formget(struct curl_httppost * form, void *userp,
                   curl_formget_callback append );
 .SH DESCRIPTION
 curl_formget() is used to serialize data previously built/appended with