fix more slice nal one frame result rtp mark error and sps pps rtp not has a mark

src/Extension/H264Rtp.h

@@ -85,6 +85,7 @@ private:
     void makeH264Rtp(const void *pData, size_t uiLen, bool bMark,  bool gop_pos, uint32_t uiStamp);
     string _sps;
     string _pps;
+    Frame::Ptr _last_frame;
 };
 
 }//namespace mediakit{