Fix #138509: Cycles: Point clouds do not render properly when using spatial splits

The bounds growth should take the radius of the points into account.

This affect BVH2, so GPU rendering without hardware ray-tracing.

Pull Request: https://projects.blender.org/blender/blender/pulls/139604

intern/cycles/bvh/split.cpp

@@ -449,11 +449,11 @@ void BVHSpatialSplit::split_point_primitive(const PointCloud *pointcloud,
   }
   point = get_unaligned_point(point);
 
-  if (point[dim] <= pos) {
+  if (point[dim] - radius <= pos) {
     left_bounds.grow(point, radius);
   }
 
-  if (point[dim] >= pos) {
+  if (point[dim] + radius >= pos) {
     right_bounds.grow(point, radius);
   }
 }