message: [cmake] Fixes Linux non-root install failure
  Install of gbc bash completion file is now to directory /etc/bash_completion.d
  Closes issue
diff: @@ -104,7 +104,7 @@ set (test_sources
  tests/TestMain.hs
  ${tests})
  -set (completion_dir /etc/bash_completion.d)
  +set (completion_dir etc/bash_completion.d)
  set (completion ${CMAKE_CURRENT_BINARY_DIR}/gbc.comp)
  set (output ${CMAKE_CURRENT_BINARY_DIR}/build/gbc/gbc${CMAKE_EXECUTABLE_SUFFIX})
  set (GBC_EXECUTABLE ${output} PARENT_SCOPE)
  @@ -128,8 +128,6 @@ install (FILES ${output}
  PERMISSIONS OWNER_EXECUTE GROUP_EXECUTE WORLD_EXECUTE
  DESTINATION bin)
  -if(EXISTS "${completion_dir}" AND IS_DIRECTORY "${completion_dir}")
  install (FILES ${completion}
  RENAME gbc
  DESTINATION ${completion_dir})
  -endif()
  