verify: add new experimental mode that requires no meta data

Should work fine, but we need to account and track trims to know
which blocks NOT to verify (or verify as zero).

Signed-off-by: Jens Axboe <axboe@kernel.dk>
diff --git a/fio.h b/fio.h
index c5e2bf1..ed793ae 100644
--- a/fio.h
+++ b/fio.h
@@ -159,6 +159,7 @@
 	unsigned int verify_async;
 	unsigned long long verify_backlog;
 	unsigned int verify_batch;
+	unsigned int experimental_verify;
 	unsigned int use_thread;
 	unsigned int unlink;
 	unsigned int do_disk_util;