The Cycles Hair Rendering panel is located in the Particle section of the Properties window.
This is bad design for a number of reasons:
- It misleads the user into thinking that these rendering settings are unique for each particle system
- It's right above "Cycles Hair Settings", which DO belong to the particle system and not the scene
- If all the user's hair objects are in linked group instances, the user must create a local particle system just to view this panel and modify these settings