Cleaning the builds on MacOSX fails

Created by: siebenkopf

The clean-up on MacOSX in the buildbot seems not to work. Apparently, the directories where it is executed: /idiap/group/torch5spro/scratch/buildbot-slave/ekhoury-x86_64/idiap-10.04-x86_64-incremental+stable/build and /idiap/group/torch5spro/scratch/buildbot-slave/ekhoury-x86_64/idiap-10.04-x86_64-incremental+stable/extras/tools are wrong in the clean scripts.

@André: Could you fix that?