Fixed the bug async socket buffer size can be zero
Fixed the bug async socket buffer size can be zero

fryderykhuang/SuperSocket,memleaks/SuperSocket,mdavid/SuperSocket,chucklu/SuperSocket,mdavid/SuperSocket,jmptrader/SuperSocket,fryderykhuang/SuperSocket,ZixiangBoy/SuperSocket,mdavid/SuperSocket,ZixiangBoy/SuperSocket,chucklu/SuperSocket,fryderykhuang/SuperSocket,jmptrader/SuperSocket,kerryjiang/SuperSocket,chucklu/SuperSocket,kerryjiang/SuperSocket,jmptrader/SuperSocket,ZixiangBoy/SuperSocket