From a purely semantic point of view, the name `CATKIN_MULTIARCH_LIB_DESTINATION` isn't great because it always contains a non arch-specific path (`CATKIN_GLOBAL_LIB_DESTINATION`) and can have multiple destinations in it. What about replacing `CATKIN_MULTIARCH_LIB_DESTINATION` with `CATKIN_LIB_ENVIRONMENT_PATHS` or something like that which is more descriptive of the contents and plural.