Suppress packaging warning

Suppress packaging warning

Only under Ubuntu Lucid the rpm packaging step mistakenly adds
the following files twice to the package because of the /lib
naming convention.  This is harmless but results in a warning
which the buildot flags as a failure.  Suppress this warning.

  warning: File listed twice: /lib/udev/rules.d
  warning: File listed twice: /lib/udev/rules.d/60-zpool.rules
  warning: File listed twice: /lib/udev/rules.d/60-zvol.rules
  warning: File listed twice: /lib/udev/rules.d/90-zfs.rules
  warning: File listed twice: /lib/udev/sas_switch_id
  warning: File listed twice: /lib/udev/zpool_id
  warning: File listed twice: /lib/udev/zvol_id

Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>