修复webrtc simulcast推流崩溃的bug

ZLToolKit @ a827f0bd

-Subproject commit 36d1122f42ab6b92d0ca8f57df0462acc632efc7
+Subproject commit a827f0bdcb4221c19ab1a243ebd1f01fa7dc50f2

webrtc/WebRtcTransport.cpp

@@ -436,8 +436,11 @@ void WebRtcTransportImp::onStartWebRTC() {
         if (m_offer->type != TrackApplication) {
             //记录rtp ext类型与id的关系，方便接收或发送rtp时修改rtp ext id
             track->rtp_ext_ctx = std::make_shared<RtpExtContext>(*m_offer);
-            track->rtp_ext_ctx->setOnGetRtp([this, &track](uint8_t pt, uint32_t ssrc, const string &rid) {
+            weak_ptr<MediaTrack> weak_track = track;
+            track->rtp_ext_ctx->setOnGetRtp([this, weak_track](uint8_t pt, uint32_t ssrc, const string &rid) {
                 //ssrc --> MediaTrack
+                auto track = weak_track.lock();
+                assert(track);
                 _ssrc_to_track[ssrc] = track;
                 InfoL << "get rtp, pt:" << (int) pt << ", ssrc:" << ssrc << ", rid:" << rid;
             });