zfs redact fails when dnodesize=auto

Add handling to dmu_object_next for the case where *objectp == 0.

Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
Closes openzfs#14479

module/zfs/dmu_object.c

@@ -409,6 +409,8 @@ dmu_object_next(objset_t *os, uint64_t *objectp, boolean_t hole, uint64_t txg)
 		 * hand off to dnode_next_offset() for further scanning.
 		 */
 		while (i <= last_obj) {
+			if (i == 0)
+				return (SET_ERROR(ESRCH));
 			error = dmu_object_info(os, i, &doi);
 			if (error == ENOENT) {
 				if (hole) {