add pthread check only for thread mode
add pthread check only for thread mode

ycaihua/tcpcopy,caosiyang/tcpcopy,u20024804/tcpcopy,horryq/tcpcopy,horryq/tcpcopy,liviusATnetskope/second,wfxiang08/tcpcopy,daodaoliang/tcpcopy,liviusATnetskope/second,sshling/tcpcopy,eliteYang/tcpcopy,daodaoliang/tcpcopy,caosiyang/tcpcopy,eliteYang/tcpcopy,u20024804/tcpcopy,ycaihua/tcpcopy,sshling/tcpcopy,wfxiang08/tcpcopy,left2right/tcpcopy,left2right/tcpcopy