rots-utils: implement a temporary threshold.

source/verify.c

@@ -238,5 +238,9 @@ int do_verify(int argc, char *argv[])
 
 	printf("%zu/%zu signatures are correct.\n", count, total);
 
+	/* TODO: implement a configurable threshold. */
+	if (count < total)
+		return -1;
+
 	return 0;
 }