blktrace: skip notify traces

Fio will not interpret them correctly, resulting in weird behaviour
(like replaying that seems to hang, but is merely just waiting for a
very long time).

Fixes the issue reported by Joshua Root.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/blktrace.c b/blktrace.c
index b4d05c7..58f28ce 100644
--- a/blktrace.c
+++ b/blktrace.c
@@ -281,6 +281,8 @@
 			log_err("fio: discarded %d of %d\n", ret, t.pdu_len);
 			goto err;
 		}
+		if (t.action & BLK_TC_ACT(BLK_TC_NOTIFY))
+			continue;
 		if (!ttime) {
 			ttime = t.time;
 			cpu = t.cpu;