layers:  Handle null fence objects in validation
layers:  Handle null fence objects in validation

QueueSubmit can be called with a NULL fence object, updated validation
to correctly handle this case.

sashinde/VulkanTools,sashinde/VulkanTools,Radamanthe/VulkanSamples,sashinde/VulkanTools,Radamanthe/VulkanSamples,elongbug/Vulkan-LoaderAndValidationLayers,sashinde/VulkanTools,elongbug/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,critsec/Vulkan-LoaderAndValidationLayers,Radamanthe/VulkanSamples,critsec/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,Radamanthe/VulkanSamples,Radamanthe/VulkanSamples,elongbug/Vulkan-LoaderAndValidationLayers,critsec/Vulkan-LoaderAndValidationLayers,elongbug/Vulkan-LoaderAndValidationLayers,Radamanthe/VulkanSamples,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,critsec/Vulkan-LoaderAndValidationLayers