WinUtils: Remove purged functions from header

Functions moved to FileUtils on 4de3b9484051483f6f0329f1ec0c3feef325045c

Change-Id: I6e8690e8f0cce1bc7162b24d6c7d87d31a724ad8
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@digia.com>