OpenXR Monado compositor处理应用layers(cheduled-＞delivered)

OpenXR Monado compositor处理应用的layer，scheduled->delivered 

＠src/xrt/targets/common/target_instance.c
t_instance_create_system
＠src/xrt/compositor/main/comp_compositor.ccomp_main_create_system_compositor＠src/xrt/compositor/multi/comp_multi_system.ccomp_multi_create_system_compositoros_thread_helper_start(&msc->oth, thread_func, msc);pthread_create(&oth->thread, NULL, func, ptr);thread_funcmulti_main_loop/* xc 获取的是 multi_system_compositor.xrt_compositor_native.xrt_compositor，与APP的xrt_compositor是不一样的 */struct xrt_compositor *xc = &msc->xcn->