Fix chaining issue in openxr_load_properties()

[keveleigh]

Looking through this chain, it seems like it converges on .foveated_varjo from two directions:

1. The normal chain from .system down, ending with a link from .foveated_varjo to .color_space_fb
2. A chain from the bottom of this list, from .space_warp_fb up through to .foveated_varjo

.space_warp_fb doesn't appear to be chained to anything, so, as far as I can tell, this chain seems like it won't be passed into the xrGetSystemProperties call.

Please let me know if I'm reading this wrong or missing something! I don't have a headset with me that might resolve any of these, so I'm currently unable to test the actual resolution. I should be able to test on Tuesday though!

[maluoi]

Yeah, this is definitely a bug, thanks for catching this one! I did test this on a device, and was indeed seeing good results.

I think in the future I'll switch this over to this kind of pattern, which should hold up a lot better, less error prone:

result.hand_tracking.next = result.system.next; result.system.next = &result.hand_tracking;
result.hand_mesh    .next = result.system.next; result.system.next = &result.hand_mesh;