message: Fix check for Linux
diff: @@ -57,10 +57,10 @@ target_link_libraries(avogadroiopython
  install(TARGETS avogadroiopython LIBRARY COMPONENT python DESTINATION "${_python_module_install_dir}")
  # Set the RPATH so the dependent libraries can be found in the wheel.
  -if (LINUX)
  - set(_rpath_value "$ORIGIN")
  -elseif(APPLE)
  +if(APPLE)
  set(_rpath_value "@loader_path")
  +elseif(UNIX)
  + set(_rpath_value "$ORIGIN")
  endif()
  if (NOT WIN32)
  