Fix 'zpool history' sometimes fails without reporting any error

The libzfs would printing an error messages by itself when the ioctl call
failed, but not when the nvlist decoding has failed.

Signed-off-by: WHR <msl0000023508@gmail.com>

cmd/zpool/zpool_main.c

@@ -9477,8 +9477,16 @@ get_history_one(zpool_handle_t *zhp, void *data)
 	(void) printf(gettext("History for '%s':\n"), zpool_get_name(zhp));
 
 	while (!eof) {
-		if ((ret = zpool_get_history(zhp, &nvhis, &off, &eof)) != 0)
+		if ((ret = zpool_get_history(zhp, &nvhis, &off, &eof)) != 0) {
+			if (ret > 0) {
+				/* ret will be errno when the error message
+				 * didn't get printed by libzfs itself. */
+				(void) fprintf(stderr, gettext("cannot get "
+				    "history for pool '%s': %s\n"),
+				    zpool_get_name(zhp), strerror(ret));
+			}
 			return (ret);
+		}
 
 		print_history_records(nvhis, cb);
 		nvlist_free(nvhis);