SteamVR: VK_EXT_display_control crashes in core_validation due to not handling vkRegisterDisplayEventEXT fence

[danginsburg]

When we enable validation with SteamVR in direct mode we end up getting a crash. The crash occurs because vkRegisterDisplayEventEXT returns a VkFence that core_validation is not aware of. When we attempt to wait on the fence, we get a crash with the following call stack where fence_state is nullptr because GetFenceNode returns null. vkRegisterDisplayEventEXT needs to be implemented so that the fence object it creates is tracked.

1 core_validation::VerifyQueueStateToFence core_validation.cpp 2534 0x7f94a5576f5d
2 core_validation::PreCallValidateWaitForFences core_validation.cpp 3298 0x7f94a557b6f8
3 core_validation::WaitForFences core_validation.cpp 3320 0x7f94a557b7d6
4 object_tracker::WaitForFences object_tracker.cpp 705 0x7f94a50244d5
5 parameter_validation::vkWaitForFences parameter_validation.cpp 2916 0x7f94a4a5fb1d
6 threading::WaitForFences thread_check.h 677 0x7f94a45214e9
7 vkWaitForFences trampoline.c 1199 0x7f94b05c16a7
8 CVulkanDirectModeVblankThread::Run hmdwindowsdl.cpp 125 0x473ec0
9 SteamThreadTools::CThread::ThreadProc threadtools.cpp 4182 0x5b3ffc
10 start_thread pthread_create.c 463 0x7f94aee466db
11 clone clone.S 95 0x7f94aeb6f88f

[danginsburg]

Confirmed fixed, closing.