This package does not need catkin at build time to build because catkin is not invoked from the `CMakeLists.txt`, and so the missing `build*_depend` on catkin is intentional. The `run_depend` on catkin is to ensure that `setup.*sh` files are installed when the packages are installed from debs, otherwise you might end up with something like only `opencv` in `/opt/ros/groovy` without the `setup.*sh` files need to add that prefix to the path's.