There were to copies of stdosl.h one from stock OSL
and one in the cycles tree augmented with cycles
specific closures.
moved the cycles ones to stdcycles.h and copied
the stock stdosl.h and accompanying headers from
the OSL shader folder.
for further details see D6812.
Reviewed By: brecht
Differential Revision: https://developer.blender.org/D6812
Similar to the Principled BSDF, this should make it easier to set up volume
materials. Smoke and fire can be rendererd with just a single principled
volume node, the appropriate attributes will be used when available. The node
also works for simpler homogeneous volumes like water or mist.
Differential Revision: https://developer.blender.org/D3033
