the postsize is an off_t so use the proper printf format to output the

content-length when doing multipart posts

lib/http.c

@@ -1487,7 +1487,7 @@ CURLcode Curl_http(struct connectdata *conn)
       if(!conn->bits.upload_chunky)
         /* only add Content-Length if not uploading chunked */
         add_bufferf(req_buffer,
-                    "Content-Length: %d\r\n", http->postsize);
+                    "Content-Length: %" FORMAT_OFF_T "\r\n", http->postsize);
 
       if(!checkheaders(data, "Expect:")) {
         /* if not disabled explicitly we add a Expect: 100-continue