MINOR: log: add a tag for amount of bytes uploaded from client to server

For POST, PUT, CONNECT or tunnelled connections, it's annoying not to have
the amount of uploaded bytes in the logs. %U now reports this value.
diff --git a/include/types/log.h b/include/types/log.h
index ce0c717..c81ab0d 100644
--- a/include/types/log.h
+++ b/include/types/log.h
@@ -65,6 +65,7 @@
 	LOG_FMT_BACKEND,
 	LOG_FMT_SERVER,
 	LOG_FMT_BYTES,
+	LOG_FMT_BYTES_UP,
 	LOG_FMT_T,
 	LOG_FMT_TQ,
 	LOG_FMT_TW,