Two different types for `ApiLayerCreateInfo` in openxr-sys

[yshui]

There's openxr_sys::loader::ApiLayerCreateInfo and openxr_sys::ApiLayerCreateInfo. One generated and the other written by hand I assume?

What's the reason for having two copies?

Also note openxr_sys::LoaderInterfaceStructs, all the associated constants have their first letters cutoff for some reason?

[Ralith]

All unintended; fixes welcome!