Add ASSERT_POD for most objects
diff --git a/src/hb-buffer-private.hh b/src/hb-buffer-private.hh
index fb1c801..b539f26 100644
--- a/src/hb-buffer-private.hh
+++ b/src/hb-buffer-private.hh
@@ -44,11 +44,13 @@
     hb_direction_t      direction;
     hb_script_t         script;
     hb_language_t       language;
+    ASSERT_POD ();
 } hb_segment_properties_t;
 
 
 struct _hb_buffer_t {
   hb_object_header_t header;
+  ASSERT_POD ();
 
   /* Information about how the text in the buffer should be treated */