This makes it possible to move some parts of evaluation from host to the device
and hopefully reduce memory usage by avoid having full RGBA buffer on the host.
Reviewers: juicyfruit, lukasstockner97, brecht
Reviewed By: lukasstockner97, brecht
Differential Revision: https://developer.blender.org/D1702
Main goal is to make kernel signatures editing easier and less prone to the
errors caused by missing function signature update or so.
This will also make it easier to add new CPU architectures.
Reviewers: juicyfruit, dingto, lukasstockner97, brecht
Reviewed By: dingto, lukasstockner97, brecht
Differential Revision: https://developer.blender.org/D1703
