Fix: frame freezing on Windows (#2931)

[awa-vr]

Fixes issue #2931 for Windows users.

This also fixes the issue for v20.14.1 (see this branch), so maybe a v20.14.2 to fix this issue before v21 comes out could be nice.

[The-personified-devil]

@zmerp What's your take on this? Doesn't look like a good solution to me but if it works it works, maybe?

[awa-vr]

I mean to be fair the comment above the change was a todo. But I've been using it for about 3 months now without any new issues, and the frame freezing went away.

Also I've tried changing stuff more deeply related to vsync and stuff, but it either didn't work or made it worse.

[zmerp]

The only reason I think this would fix freezing is if SteamVR started consistently taking more than 10ms to unlock the texture. I guess this happens when for some reason SteamVR always uses the same texture instead of cycling them in the swapchains (there might be some other issues with frame indices handling like Vixea previously reported). I think this PR should work, but I would like to see tested also a timeout of 50ms. 50ms is definitely above any normal frametime (even at 30fps), and it's smaller enough that it will not cause any unnecessary waiting during shutdown. if that doesn't work let's try 100ms. @awa-vr

[awa-vr]

I don't have a ton of time to test stuff now so it might take a bit of time to test different timeouts.

[zmerp]

That's alright. Unfortunately I can't reproduce this issue myself