message: remove unused Embree headers
diff: #include "ospray/common/Ray.ih"
  #include "ospray/geometry/Geometry.ih"
  #include "ospray/math/vec.ih"
  -// embree
  -#include "embree2/rtcore.isph"
  -#include "embree2/rtcore_geometry_user.isph"
  -#include "embree2/rtcore_scene.isph"
  /*! BVH node for a MinMaxBVH2 */
  struct MinMaxBVH2Node
  