TChannelRequest: factor out #checkTimeout
TChannelRequest: factor out #checkTimeout

hustxiaoc/tchannel,chenwenbin928/tchannel,vanloswang/tchannel,benfleis/tchannel,hustxiaoc/tchannel,savaki/tchannel,sasa233/tchannel,savaki/tchannel,sasa233/tchannel,chenwenbin928/tchannel,vanloswang/tchannel,bunnyblue/tchannel,RyanTech/tchannel,bunnyblue/tchannel,sasa233/tchannel,hustxiaoc/tchannel,RyanTech/tchannel,Zirpon/tchannel,RyanTech/tchannel,i/tchannel,Zirpon/tchannel,Zirpon/tchannel,savaki/tchannel,vanloswang/tchannel,bunnyblue/tchannel,i/tchannel,benfleis/tchannel,i/tchannel,chenwenbin928/tchannel,benfleis/tchannel