Save VSync setting

[tobbi]

Fixes #2780

I'm not sure if this is the right approach, as we seem to be checking for the best possible vsync value earlier and picking one.

What's saved is: boolean yes / no: Check for vsync and not the exact vsync value.

[MatusGuy]

Thanks tobbi

[Vankata453]

At a first glance, I'd assume the issue is that VideoSystem has already been destroyed by the time the config is destroyed.

[tobbi]

Okay, please try again.

[tobbi]

Wait, I fucked up.