Fix unlikely leaks

src/hb-ft.cc

@@ -496,8 +496,10 @@ reference_table  (hb_face_t *face HB_UNUSED, hb_tag_t tag, void *user_data)
     return nullptr;
 
   error = FT_Load_Sfnt_Table (ft_face, tag, 0, buffer, &length);
-  if (error)
+  if (error) {
+    free ((void*)buffer);
     return nullptr;
+  }
 
   return hb_blob_create ((const char *) buffer, length,
 			 HB_MEMORY_MODE_WRITABLE,

src/hb-ot-shape.cc

@@ -193,9 +193,11 @@ _hb_ot_shaper_shape_plan_data_create (hb_shape_plan_t    *shape_plan,
 
   if (plan->shaper->data_create) {
     plan->data = plan->shaper->data_create (plan);
-    if (unlikely (!plan->data))
+    if (unlikely (!plan->data)) {
+      free ((void*)plan);
       return nullptr;
     }
+  }
 
   return plan;
 }