Blender Git Loki

Cycles: Change confusing logic of max leaf size check

Maximal number of elements is supposed to be inclusive. That is what
it was always meant in this file and what @brecht considered still
the case in 6974b69c6172.

In fact, the commit message to that change mentions that we allowed
up to 2 curve primitives per leaf while in fact it was doing up to 1
curve primitive.

Making it real 2 primitives at a max gives about 5% slowdown for the
koro.blend scene. This is a reason why BVHParams.max_curve_leaf_size
was changed to 1 by this change.