File reset should clear random map as well

Fixes infinite loop on time based runs, where it repeatedly
fails getting a new offset.

Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/fio.h b/fio.h
index a9e2e3b..4077a5b 100644
--- a/fio.h
+++ b/fio.h
@@ -1033,6 +1033,8 @@
 {
 	f->last_free_lookup = 0;
 	f->last_pos = f->file_offset;
+	if (f->file_map)
+		memset(f->file_map, 0, f->num_maps * sizeof(int));
 }
 
 static inline void clear_error(struct thread_data *td)