include: update xgl.h with FF vertex fetch
include: update xgl.h with FF vertex fetch

https://cvs.khronos.org/svn/repos/oglc/trunk/nextgen/proposals/IMG/xgl_vertex_input_description2_img.h

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