优化MMAP相关功能

internal/caches/storage_file_ext.go

@@ -0,0 +1,9 @@
+// Copyright 2024 GoEdge CDN goedge.cdn@gmail.com. All rights reserved. Official site: https://goedge.cn .
+//go:build !plus
+
+package caches
+
+func (this *FileStorage) tryMMAPReader(isPartial bool, estimatedSize int64, path string) (Reader, error) {
+	// stub
+	return nil, nil
+}