port from agraef's commit in Pd-l2ork: debuild: Add arduino folder. commit...

port from agraef's commit in Pd-l2ork: debuild: Add arduino folder. commit e12842b2009e7d44eb41fb46ef47f0cd9f35f840

debuild/debian/install

 scripts/bash_completion/pd-l2ork	etc/bash_completion.d
 l2ork_addons/K12			usr/lib/pd-l2ork/extra
+externals/hardware/arduino		usr/lib/pd-l2ork/extra
 packages/linux_make/default.settings	usr/lib/pd-l2ork
 packages/linux_make/pd-l2ork.gif	usr/lib/pd-l2ork
 packages/linux_make/pd-l2ork*.png	usr/share/icons/hicolor/128x128/apps