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
* Rename fresnel_dielectric() to fresnel_dielectric_cos() to match SVM, easier when searching code.
* Also remove an old code comment in bsdf_reflection.h from Cycles branch days.
* Moved kernel/osl/nodes to kernel/shaders
* Renamed standard attributes to use geom:, particle:, object: prefixes
* Update stdosl.h to properly reflect the closures we support
* Fix the wrong stdosl.h being used for building shaders
* Add geom:numpolyvertices, geom:trianglevertices, geom:polyvertices attributes
