cpio: fix regression in prev commit (harmless)

diff --git a/archival/cpio.c b/archival/cpio.c
index d39640d..b447b27 100644
--- a/archival/cpio.c
+++ b/archival/cpio.c
@@ -341,11 +341,13 @@
 		argv++;
 	}
 
+	/* see get_header_cpio */
+	archive_handle->ah_priv[2] = (void*) ~(ptrdiff_t)0;
 	while (get_header_cpio(archive_handle) == EXIT_SUCCESS)
 		continue;
 
-	/* see get_header_cpio */
-	printf("%lu blocks\n", (unsigned long)(ptrdiff_t)(archive_handle->ah_priv[2]));
+	if (archive_handle->ah_priv[2] != (void*) ~(ptrdiff_t)0)
+		printf("%lu blocks\n", (unsigned long)(ptrdiff_t)(archive_handle->ah_priv[2]));
 
 	return EXIT_SUCCESS;
 }