Note in LICENSE.libyaml the specific files covered.
diff --git a/LICENSE.libyaml b/LICENSE.libyaml
index 050ced2..8da58fb 100644
--- a/LICENSE.libyaml
+++ b/LICENSE.libyaml
@@ -1,3 +1,15 @@
+The following files were ported to Go from C files of libyaml, and thus
+are still covered by their original copyright and license:
+
+ apic.go
+ emitterc.go
+ parserc.go
+ readerc.go
+ scannerc.go
+ writerc.go
+ yamlh.go
+ yamlprivateh.go
+
Copyright (c) 2006 Kirill Simonov
Permission is hereby granted, free of charge, to any person obtaining a copy of
