SMACK-419 PacketWriter: Only flush if queue is empty
SMACK-419 PacketWriter: Only flush if queue is empty

git-svn-id: 0d4d1bf2e47502aa0f0957c230a0ec7fa56198fd@13565 b35dd754-fafc-0310-a699-88a17e54d16e

vanitasvitae/Smack,mar-v-in/Smack,annovanvliet/Smack,annovanvliet/Smack,xuIcream/Smack,mar-v-in/Smack,qingsong-xu/Smack,u20024804/Smack,andrey42/Smack,vanitasvitae/smack-omemo,ishan1604/Smack,magnetsystems/message-smack,vito-c/Smack,annovanvliet/Smack,deeringc/Smack,andrey42/Smack,Tibo-lg/Smack,TTalkIM/Smack,Tibo-lg/Smack,ishan1604/Smack,dpr-odoo/Smack,mar-v-in/Smack,andrey42/Smack,ayne/Smack,Flowdalic/Smack,kkroid/OnechatSmack,vanitasvitae/smack-omemo,igniterealtime/Smack,lovely3x/Smack,igorexax3mal/Smack,chuangWu/Smack,cjpx00008/Smack,chuangWu/Smack,TTalkIM/Smack,hy9902/Smack,igniterealtime/Smack,kkroid/OnechatSmack,vanitasvitae/smack-omemo,unisontech/Smack,deeringc/Smack,igorexax3mal/Smack,xuIcream/Smack,igniterealtime/Smack,dpr-odoo/Smack,vanitasvitae/Smack,magnetsystems/message-smack,u20024804/Smack,ayne/Smack,unisontech/Smack,Flowdalic/Smack,cjpx00008/Smack,Tibo-lg/Smack,hy9902/Smack,Flowdalic/Smack,kkroid/OnechatSmack,hy9902/Smack,unisontech/Smack,opg7371/Smack,ayne/Smack,ishan1604/Smack,vanitasvitae/Smack,qingsong-xu/Smack,deeringc/Smack,lovely3x/Smack,esl/Smack,TTalkIM/Smack,dpr-odoo/Smack,esl/Smack,chuangWu/Smack,esl/Smack,u20024804/Smack,xuIcream/Smack,magnetsystems/message-smack,qingsong-xu/Smack,lovely3x/Smack,opg7371/Smack,vito-c/Smack,cjpx00008/Smack,opg7371/Smack,igorexax3mal/Smack