Install catkin packages on Arch

catkin_install.sh

# this sucks
# you will need to chmod some /opt/ros/melodic directories for make install to work...
# feel free to tell me how to actually do this

source /usr/share/ros-build-tools/clear-ros-env.sh
source /opt/ros/melodic/setup.bash
mkdir build
cd build
/usr/share/ros-build-tools/fix-python-scripts.sh -v 3 ..

cmake .. \
  -DCMAKE_BUILD_TYPE=Release \
  -DCATKIN_ENABLE_TESTING=0 \
  -DCATKIN_BUILD_BINARY_PACKAGE=ON \
  -DCMAKE_INSTALL_PREFIX=/opt/ros/melodic \
  -DPYTHON_EXECUTABLE=/usr/bin/python3 \
  -DPYTHON_INCLUDE_DIR=/usr/include/python3.8 \
  -DPYTHON_LIBRARY=/usr/lib/libpython3.8.so \
  -DPYTHON_BASENAME=.cpython-38 \
  -DSETUPTOOLS_DEB_LAYOUT=OFF

make
make install