variant with duplicate dmu_object_next

dmu_send_duplicate.c

		uint64_t obj = rwa->last_touched_object + 1;
		int free_err = 0, next_err = 0;

		while (next_err == 0) {
			dmu_object_info_t doi;

			free_err = dmu_object_info(rwa->os, obj, &doi);
			if (free_err == ENOENT) {
			  	next_err = dmu_object_next(rwa->os, &obj, FALSE, 0);        
				continue;
      			} else if (free_err != 0)
				break;

			free_err = dmu_free_long_object(rwa->os, obj);
			if (free_err != 0)
				break;

			next_err = dmu_object_next(rwa->os, &obj, FALSE, 0);
		}