[ot-font] Fix leak

https://github.com/behdad/harfbuzz/issues/139#issuecomment-147616887
diff --git a/src/hb-ot-font.cc b/src/hb-ot-font.cc
index 3d861ec..3102784 100644
--- a/src/hb-ot-font.cc
+++ b/src/hb-ot-font.cc
@@ -261,6 +261,7 @@
   ot_font->cmap.fini ();
   ot_font->h_metrics.fini ();
   ot_font->v_metrics.fini ();
+  ot_font->glyf.fini ();
 
   free (ot_font);
 }