Revert "fix overhead size"
Revert "fix overhead size"

This reverts commit 587453c881458a8a650274d44fa1cb8243ab83d7.

monokoo/shadowsocks,shadowsocksr-backup/shadowsocksr,shadowsocksr-backup/shadowsocksr,monokoo/shadowsocks,shadowsocksR-private/shadowsocksR,shadowsocksR-private/shadowsocksR