Fix leak

src/hb-shape-plan.cc

diff --git a/src/hb-shape-plan.cc b/src/hb-shape-plan.cc
index 974c370..ddfb501 100644
--- a/src/hb-shape-plan.cc
+++ b/src/hb-shape-plan.cc
@@ -148,6 +148,8 @@
 #include "hb-shaper-list.hh"
 #undef HB_SHAPER_IMPLEMENT
 
+  hb_face_destroy (shape_plan->face);
+
   free (shape_plan);
 }