http_client: fix format string mismatch (#2442)

fmt_plain expects 3 arguments, but body_len is the 4th.

Signed-off-by: Zero King <[email protected]>

Author: l2dy

src/flb_http_client.c

@@ -619,8 +619,7 @@ struct flb_http_client *flb_http_client(struct flb_upstream_conn *u_conn,
                        fmt_plain,
                        str_method,
                        uri,
-                       flags & FLB_HTTP_10 ? 0 : 1,
-                       body_len);
+                       flags & FLB_HTTP_10 ? 0 : 1);
     }
     else {
         ret = snprintf(buf, FLB_HTTP_BUF_SIZE,