Add 'f' (Finishing) flag to status output

Use this for finalizing logs when a thread is done, since
that can take a long time.

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/fio.h b/fio.h
index befdce3..a539f21 100644
--- a/fio.h
+++ b/fio.h
@@ -471,6 +471,7 @@
 	TD_PRE_READING,
 	TD_VERIFYING,
 	TD_FSYNCING,
+	TD_FINISHING,
 	TD_EXITED,
 	TD_REAPED,
 };