Reset file count when freeing files

This fixes and oops with iolog replay, and a manually specified
filename=

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/filesetup.c b/filesetup.c
index 84eaed6..2049fd6 100644
--- a/filesetup.c
+++ b/filesetup.c
@@ -1524,6 +1524,8 @@
 void free_release_files(struct thread_data *td)
 {
 	close_files(td);
+	td->o.nr_files = 0;
+	td->o.open_files = 0;
 	td->files_index = 0;
 	td->nr_normal_files = 0;
 }