Blender Git Loki

Cycles: Create proper sockets for OSL script nodes

Previously render nodes will be always created with just a VECTOR socket
type and then those sockets will try to be set as all point, vector and
normal to work around lack of such a subtype distinguishing in blender.

This change makes it so subtype is being queried from OSL itself and
proper subtupe is being used for socket.

It's still not in use for the official builds because it requires changes
applied recently on the 1.7 branch of OSL:

https://github.com/imageworks/OpenShadingLanguage/commit/f70e58f

This solves artists confusion reported in T46117.

Reviewers: #cycles, juicyfruit

Reviewed By: #cycles, juicyfruit

Subscribers: juicyfruit

Differential Revision: https://developer.blender.org/D1627