layers: Fix object tracker extension struct
layers: Fix object tracker extension struct

Change-Id: Iec29cc46df0f12d7e1da4daa18fb02d5023151b5

KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers,KhronosGroup/Vulkan-LoaderAndValidationLayers