C++: Add upgrade and downgrade scripts

Author: jketema

cpp/downgrades/af887e83a815a9cefe774ffa80e2493a1365b9e2/builtintypes.ql

@@ -0,0 +1,9 @@
+class BuiltinType extends @builtintype {
+  string toString() { none() }
+}
+
+from BuiltinType id, string name, int kind, int new_kind, int size, int sign, int alignment
+where
+  builtintypes(id, name, kind, size, sign, alignment) and
+  if kind = 62 then new_kind = 1 else new_kind = kind
+select id, name, new_kind, size, sign, alignment