Add some missing rpaths

Now that we check that we don't link with system libraries ( slapos.core!172 ) we discovered missing rpaths in our executables.

/reviewed-on !682
2 jobs for fix/proftpd-missing-rpath
Status Job ID Name Coverage
  External
running SlapOS.SlapRunner.ResilienceTest-Master.ERP5

43375:16:22

failed SlapOS.SoftwareReleases.IntegrationTest-Master

04:56:53