avcodec/avcodec_internal: fix type definition for the new functions

Fixes make checkheaders.

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

libavcodec/avcodec_internal.h

@@ -89,18 +89,18 @@ void ff_thread_flush(struct AVCodecContext *avctx);
  *
  * Parameters are the same as FFCodec.receive_frame.
  */
-int ff_thread_receive_frame(AVCodecContext *avctx, AVFrame *frame);
+int ff_thread_receive_frame(struct AVCodecContext *avctx, AVFrame *frame);
 
 /**
  * Do the actual decoding and obtain a decoded frame from the decoder, if
  * available. When frame threading is used, this is invoked by the worker
  * threads, otherwise by the top layer directly.
  */
-int ff_decode_receive_frame_internal(AVCodecContext *avctx, AVFrame *frame);
+int ff_decode_receive_frame_internal(struct AVCodecContext *avctx, AVFrame *frame);
 
 /**
  * Get a packet for decoding. This gets invoked by the worker threads.
  */
-int ff_thread_get_packet(AVCodecContext *avctx, AVPacket *pkt);
+int ff_thread_get_packet(struct AVCodecContext *avctx, AVPacket *pkt);
 
 #endif // AVCODEC_AVCODEC_INTERNAL_H