fix bug 某种情况下，当客户端全部断开后，边缘服务器回源线程（EdgeIngester/EdgeForwarder）没有被断开。
fix bug
某种情况下，当客户端全部断开后，边缘服务器回源线程（EdgeIngester/EdgeForwarder）没有被断开。

tempbottle/simple-rtmp-server,dymx101/simple-rtmp-server,oceanho/simple-rtmp-server,tribbiani/srs,tempbottle/simple-rtmp-server,Vincent0209/simple-rtmp-server,oceanho/simple-rtmp-server,lewdon/srs,chengjunjian/simple-rtmp-server,tribbiani/srs,dymx101/simple-rtmp-server,zhiliaoniu/simple-rtmp-server,antonioparisi/srs,winlinvip/srs,chengjunjian/simple-rtmp-server,keyanmca/srs-May-2014,tribbiani/srs,zhiliaoniu/simple-rtmp-server,chengjunjian/simple-rtmp-server,avplus/srs,winlinvip/srs,oceanho/simple-rtmp-server,lewdon/srs,myself659/simple-rtmp-server,lewdon/srs,winlinvip/srs,ossrs/srs,keyanmca/srs-May-2014,zhiliaoniu/simple-rtmp-server,chengjunjian/simple-rtmp-server,lewdon/srs,ossrs/srs,icevl/srs,drunknbass/srs,icevl/srs,Robinson10240/simple-rtmp-server,avplus/srs,drunknbass/srs,drunknbass/srs,keyanmca/srs-May-2014,myself659/simple-rtmp-server,antonioparisi/srs,tempbottle/simple-rtmp-server,ossrs/srs,dymx101/simple-rtmp-server,lewdon/srs,avplus/srs,dymx101/simple-rtmp-server,Vincent0209/simple-rtmp-server,icevl/srs,oceanho/simple-rtmp-server,antonioparisi/srs,oceanho/simple-rtmp-server,antonioparisi/srs,winlinvip/simple-rtmp-server,Robinson10240/simple-rtmp-server,myself659/simple-rtmp-server,tribbiani/srs,myself659/simple-rtmp-server,avplus/srs,tempbottle/simple-rtmp-server,zhiliaoniu/simple-rtmp-server,Vincent0209/simple-rtmp-server,icevl/srs,drunknbass/srs,Robinson10240/simple-rtmp-server,drunknbass/srs,antonioparisi/srs,zhiliaoniu/simple-rtmp-server,avplus/srs,myself659/simple-rtmp-server,keyanmca/srs-May-2014,Vincent0209/simple-rtmp-server,myself659/simple-rtmp-server,tribbiani/srs,lewdon/srs,Vincent0209/simple-rtmp-server,keyanmca/srs-May-2014,Robinson10240/simple-rtmp-server,chengjunjian/simple-rtmp-server,avplus/srs,tempbottle/simple-rtmp-server,oceanho/simple-rtmp-server,ossrs/srs,tribbiani/srs,keyanmca/srs-May-2014,zhiliaoniu/simple-rtmp-server,ossrs/srs,winlinvip/srs,ossrs/srs,Robinson10240/simple-rtmp-server,chengjunjian/simple-rtmp-server,avplus/srs,winlinvip/srs,tribbiani/srs,antonioparisi/srs,icevl/srs,dymx101/simple-rtmp-server,drunknbass/srs,tempbottle/simple-rtmp-server,icevl/srs,Vincent0209/simple-rtmp-server,dymx101/simple-rtmp-server,winlinvip/srs,Robinson10240/simple-rtmp-server