CODE: remove unused variables

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6421 8aca7d54-2c30-db11-9de9-000461428c89
CHG: only include osx.mk if OSTYPE == mac

git-svn-id: svn://tron.homeunix.org/simutrans/simutrans/trunk@6422 8aca7d54-2c30-db11-9de9-000461428c89