[test-buffer-serialize] Handle too-small out buffer

Need to handle too-small in buffer still.
diff --git a/src/test-buffer-serialize.cc b/src/test-buffer-serialize.cc
index 8a88792..248c464 100644
--- a/src/test-buffer-serialize.cc
+++ b/src/test-buffer-serialize.cc
@@ -56,10 +56,6 @@
   hb_font_t *font = hb_font_create (face);
   hb_face_destroy (face);
   hb_font_set_scale (font, upem, upem);
-  //hb_ot_font_set_funcs (font);
-#ifdef HAVE_FREETYPE
-  //hb_ft_font_set_funcs (font);
-#endif
 
   hb_buffer_t *buf;
   buf = hb_buffer_create ();
@@ -78,11 +74,17 @@
     if (*p && *p != '\n')
       ret = false;
 
-    hb_buffer_serialize_glyphs (buf, 0, hb_buffer_get_length (buf),
-				out, sizeof (out), nullptr,
-				font, HB_BUFFER_SERIALIZE_FORMAT_TEXT,
-				HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS);
-    puts (out);
+    unsigned count = hb_buffer_get_length (buf);
+    for (unsigned offset = 0; offset < count;)
+    {
+      unsigned len;
+      offset += hb_buffer_serialize_glyphs (buf, offset, count,
+					    out, sizeof (out), &len,
+					    font, HB_BUFFER_SERIALIZE_FORMAT_TEXT,
+					    HB_BUFFER_SERIALIZE_FLAG_GLYPH_FLAGS);
+      fwrite (out, 1, len, stdout);
+    }
+    fputs ("\n", stdout);
   }
 
   hb_buffer_destroy (buf);