Fix read_iolog

Caveat - it only works with 1 file, unfortunately. Will need a format
change to get that right.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/log.c b/log.c
index 45be5fb..de3b759 100644
--- a/log.c
+++ b/log.c
@@ -19,6 +19,11 @@
 		io_u->buflen = ipo->len;
 		io_u->ddir = ipo->ddir;
 		io_u->file = ipo->file;
+		/*
+		 * work around, this needs a format change to work for > 1 file
+		 */
+		if (!io_u->file)
+			io_u->file = &td->files[0];
 		free(ipo);
 		return 0;
 	}