The OpenCV GPU Module is intented to process data on a Nvidia GPU (read: Graphic card). The Galileo has no Nvidia GPU nor a GPU at all. So the module (represented by the libopencv_gpu.so shared library) makes no sense on a Galileo and isn't available. You may try to compile OpenCV with GPU support to satisfy the requirements by this program. But this wouldn't make much sense, because you still have no Nvidia GPU on the Galileo.