wined3d: Conditionally update saved window state in fullscreen mode.
For Assassin's Creed Syndicate. When switching from fullscreen to a smaller windowed resolution, it calls SetWindowPos() centering the window, then calls ResizeTarget() and finally SetFullscreenState(), and expects the window to preserve the position.
Window style handling is a bit iffy because of the manipulation we do when entering fullscreen, but that's not really new.
Edited by Matteo Bruni