Enclosure LED fixes

Enclosure LED fixes

- Pass $VDEV_ENC_SYSFS_PATH to 'zpool [iostat|status] -c' to include
  enclosure LED sysfs path.

- Set LEDs correctly after import.  This includes clearing any erroniously
  set LEDs prior to the import, and setting the LED for any UNAVAIL drives.

- Include symlink for vdev_attach-led.sh in Makefile.am.

- Print the VDEV path in all-syslog.sh, and fix it so the pool GUID actually
  prints.

Reviewed-by: Don Brady <don.brady@intel.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #5716
Closes #5751