Blender Git Loki

Cycles: Use a function to calculate sin and cos at the same time.

Only enabled for gcc atm, tested on an Ivy Bridge CPU with gcc 4.8.
This gives me about 4% speedup in simple scenes like the cornell_box.blend and color_ramp.blend.

Can probably also be enabled for clang and msvc later, they have a sincos() function as well.

THis commit also contains small cleanup and a compile fix for the AVX2 kernel after merge.