Blender Git Loki

Cycles: Add some utility tests using GTests

This is an initial move to have unittests to at least cover
utility functions, which then could be extended further to
test such areas as shader optimization and such.

Currently only based on initial "infrastructure" layout and
writing tests needed to test the no-boost patch.

Note: This patch starts to use "<dir>/<header>.h" notation
for the include statements which i just got used to do in
other projects. Something what would be cool to use globally
in the code eventually.

Reviewers: dingto, juicyfruit, lukasstockner97, brecht

Reviewed By: brecht

Differential Revision: https://developer.blender.org/D1770