Removed unused function

Author: yhirose

peglib.h

@@ -2312,13 +2312,6 @@ struct AstOptimizer
     const std::vector<std::string> filters_;
 };
 
-template <typename T>
-static std::shared_ptr<T> optimize_ast(
-    std::shared_ptr<T> ast,
-    const std::vector<std::string>& filters = {}) {
-    return AstOptimizer(true, filters).optimize(ast);
-}
-
 struct EmptyType {};
 typedef AstBase<EmptyType> Ast;