basic : remove useless class pre declaration

Change-Id: Iba78fb4d28651b298ed6ec5e53b30b2afebb28a6
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/110203
Tested-by: Jenkins
Reviewed-by: Noel Grandin <noel.grandin@collabora.co.uk>
diff --git a/basic/source/inc/filefmt.hxx b/basic/source/inc/filefmt.hxx
index f6cc8e1..3460b1a 100644
--- a/basic/source/inc/filefmt.hxx
+++ b/basic/source/inc/filefmt.hxx
@@ -19,8 +19,6 @@

#pragma once

class SvStream;

// Version  2: data type of the return value for publics
// Version  3: new opcodes
// Version  4: new opcodes