- Remove visionOS from multi-platform builds because it
requires Xcode 15+ and will abort a multi-platform build.
- Define TARGET_OS_XR for older SDK's.
- A number of SDK deprecation warnings remain when building for visionOS.
These cannot be removed without significant refactoring.
- Build visionOS dependencies for Release build by default.
- Fix local variable initialization warning (unrelated).
6374d9d29b