remove unnecessary io usage i introduced to ui.backend

diff --git a/extra/ui/backend/backend.factor b/extra/ui/backend/backend.factor
index 68d280fc505bc48b82298f60f9f4076c0f65495e..0840d07cbc12fb0c9788a15f187d26e3bde869b1 100755 (executable)
--- a/extra/ui/backend/backend.factor
+++ b/extra/ui/backend/backend.factor
@@ -1,6 +1,6 @@
 ! Copyright (C) 2006, 2007 Slava Pestov.
 ! See http://factorcode.org/license.txt for BSD license.
-USING: io kernel namespaces opengl opengl.gl ;
+USING: kernel namespaces opengl opengl.gl ;
 IN: ui.backend
 
 SYMBOL: ui-backend