More keyboard improvements

[slouken]

Enable raw keyboard events on Windows by default

Added support for events from distinct keyboards

[sezero]

Applied 693c75e to fix linkage if Xinput2 isn't available

[slouken]

Thanks!

[0x1F9F1]

Started getting some crashes in WIN_PollRawInput after this. I think because it assumes all events are of size data->rawinput_size, which is no longer true.

Edit: Maybe this should've been #9361

[slouken]

Started getting some crashes in WIN_PollRawInput after this. I think because it assumes all events are of size data->rawinput_size, which is no longer true.

Fixed, thanks!