Blender Git Loki

Cycles: Cleanup of OpenCL split kernel routines

The idea is to switch from allocating separate buffers for shader data's
structure of arrays to allocating one huge memory block and do some index
trickery to make it accessed as SOA.

This saves quite reasonable amount of lines of code in device_opencl and
also makes it possible to get rid of special declaration of ShaderData
structure.

As a side effect it also makes it easier to experiment with SOA vs. AOS
for split kernel.

Works fine here on NVidia GTX580, Intel CPU amd AMD Fiji cards.

Reviewers: #cycles, brecht, juicyfruit, dingto

Differential Revision: https://developer.blender.org/D1593