Update CMakeLists.txt for pinocchio

[mayataka]

Now the CMake packaging for pinocchio is updated and improved. I think it is nice to fix CMakeLists.txt in RobotManipulator example. I've done it in my branch, so I'd like to merge the change into this master branch if @deng-haoyang allows it.

[yakunsjtu]

Hi @mayataka , could you provide the branch link? Thanks!