v2/call: de-dupe flag definitions
v2/call: de-dupe flag definitions

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