Blender Git Loki

Fix T47207: Material shading incorrectly handles colorramp node

The issue was introduced by a fix for T44713 which only made GLSL
consistent with Cycles.

Now we do have conditional averaging or proper luma weighting based
on whether we're new old old shading system. Not totally ideal but
should work for until we re-design viewport possibly breaking how
Blender Internal does implicit conversion.