Rescan enclosure sysfs path on import

When you create a pool, zfs writes vd->vdev_enc_sysfs_path with the
enclosure sysfs path to the fault LEDs, like:

    vdev_enc_sysfs_path = /sys/class/enclosure/0:0:1:0/SLOT8

However, this enclosure path doesn't get updated on successive imports
even if enclosure path to the disk changes.  This patch fixes the issue.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Tony Hutter <hutter2@llnl.gov>
Closes #11950 
Closes #12095

cmd/zpool/zpool_util.h

@@ -27,6 +27,7 @@
 
 #include <libnvpair.h>
 #include <libzfs.h>
+#include <libzutil.h>
 
 #ifdef	__cplusplus
 extern "C" {
@@ -68,7 +69,6 @@ int for_each_pool(int, char **, boolean_t unavail, zprop_list_t **,
     boolean_t, zpool_iter_f, void *);
 
 /* Vdev list functions */
-typedef int (*pool_vdev_iter_f)(zpool_handle_t *, nvlist_t *, void *);
 int for_each_vdev(zpool_handle_t *zhp, pool_vdev_iter_f func, void *data);
 
 typedef struct zpool_list zpool_list_t;