layers: Add codegen header version
layers: Add codegen header version

Add an integer constant to the parameter_validation layer's generated
code to specify the header/XML version from which the code was
generated.

Change-Id: Id690962856130007a24732a478ffa9c28f774b8f

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