Add `ODIN_PLATFORM_SUBTARGET_IOS` builtin constant which evaluated to `true` when the platform is `Darwin` and the subtarget it either `iPhone` or `iPhoneSimulator`
Add `ODIN_PLATFORM_SUBTARGET_IOS` builtin constant which evaluated to `true` when the platform is `Darwin` and the subtarget it either `iPhone` or `iPhoneSimulator`