No API changes, and only minimal consistency changes to the spec/registry.
Mostly an update for tooling, layers, loader, and sample code.
Header version has been bumped to 43, but no symbols that should have actually been in use have changed.
The OpenXR-Docs repo now contains the scripts and sources needed to build
the specification output files.
### Internal Issues
- General, Build, Other
- Unify (for the most part) the OpenXR and Vulkan generator scripts. (internal MR 1166)
- Avoid dllexport for all apps compiled with `openxr_platform_defines.h` (internal MR 1187)
- API Registry and Headers
- Remove impossible and undocumented error codes. (internal MR 1185 and 1189)
- Mark layers in `XrFrameEndInfo` as optional. (internal MR 1151, internal issue 899)
- Remove unused windows types from `openxr_platform.h` (internal MR 1197)
- Make `openxr_platform.h` include `openxr.h` on which it depends. (internal MR 1140, internal issue 918)
- Remove unused, undocumented defines. (internal MR 1238, internal issue 1012)
Ryan Pavlik