Fix iOS build

openVulkanoCpp/Host/iOS/OpenVulkanoViewController.mm

@@ -58,6 +58,9 @@ public:
 	IOpenGlWindow * GetOpenGlWindow() override { return nullptr; }
 	IVulkanWindow * GetVulkanWindow() override { return this; }
 	
+	bool WindowHasBeenDestroyed() const override { return false; }
+	void SetWindowHasBeenDestroyed() override {}
+	
 	void* GetNativeWindowHandle() override { return caMetalLayer; }
 	
 	vk::SurfaceKHR CreateSurface(const vk::Instance &instance, const vk::AllocationCallbacks *pAllocator = nullptr) override