[klone] io_t codecs flush code moved to io_underflow
[klone] io_t codecs flush code moved to io_underflow

xunmengfeng/klone,xunmengfeng/klone,larsthegeek/klone,larsthegeek/klone,koanlogic/klone,koanlogic/klone,koanlogic/klone,larsthegeek/klone