avcodec/decode: flush the internal bsfs instead of constantly reinitalizing them

Initialize the bsfs once when opening the codec and uninitialize them once when
closing it, instead of at every codec flush/seek.

Signed-off-by: James Almer <jamrial@gmail.com>

libavcodec/decode.h

@@ -64,6 +64,8 @@ typedef struct FrameDecodeData {
  */
 int ff_decode_get_packet(AVCodecContext *avctx, AVPacket *pkt);
 
+int ff_decode_bsfs_init(AVCodecContext *avctx);
+
 void ff_decode_bsfs_uninit(AVCodecContext *avctx);
 
 /**