Use nullptr instead of NULL
diff --git a/src/hb-unicode.cc b/src/hb-unicode.cc
index d553a71..726baeb 100644
--- a/src/hb-unicode.cc
+++ b/src/hb-unicode.cc
@@ -188,7 +188,7 @@
 const hb_unicode_funcs_t _hb_unicode_funcs_nil = {
   HB_OBJECT_HEADER_STATIC,
 
-  NULL, /* parent */
+  nullptr, /* parent */
   true, /* immutable */
   {
 #define HB_UNICODE_FUNC_IMPLEMENT(name) hb_unicode_##name##_nil,
@@ -365,7 +365,7 @@
   } else {									\
     ufuncs->func.name = ufuncs->parent->func.name;				\
     ufuncs->user_data.name = ufuncs->parent->user_data.name;			\
-    ufuncs->destroy.name = NULL;						\
+    ufuncs->destroy.name = nullptr;						\
   }										\
 }