Add an encoder method for encoding the SPS/PPS without encoding a frame

This is useful if using a muxer that requires the SPS/PPS to be
available before the first frame is encoded.

codec/api/svc/codec_api.h

@@ -52,6 +52,11 @@ class ISVCEncoder {
   virtual int EncodeFrame (const unsigned char* kpSrc, SFrameBSInfo* pBsInfo) = 0;
   virtual int EncodeFrame (const SSourcePicture**   kppSrcPicList, int nSrcPicNum, SFrameBSInfo* pBsInfo) = 0;
 
+  /*
+   * return: 0 - success; otherwise - failed;
+   */
+  virtual int EncodeParameterSets (SFrameBSInfo* pBsInfo) = 0;
+
   /*
    * return: 0 - success; otherwise - failed;
    */