Add missing Normalize() call in PerspectiveCamera::GenerateRay().  (Ke Xu)
Add missing Normalize() call in PerspectiveCamera::GenerateRay().  (Ke Xu)

patwonder/pbrt-v2-skin,patwonder/pbrt-v2-skin,patwonder/pbrt-v2-skin,patwonder/pbrt-v2-skin,patwonder/pbrt-v2-skin