Implement avcodec_decode_video2(), _audio3() and _subtitle2() which takes an
AVPacket argument rather than a const uint8_t *buf + int buf_size. This allows
passing of packet-specific flags from demuxer to decoder, such as the keyframe
flag, which appears necessary to playback corePNG P-frames.

Patch by Thilo Borgmann thilo.borgmann googlemail com, see also the thread
"Google Summer of Code participation" on the mailinglist.

Originally committed as revision 18351 to svn://svn.ffmpeg.org/ffmpeg/trunk
diff --git a/libavcodec/indeo2.c b/libavcodec/indeo2.c
index 40c561a..75b9ee9 100644
--- a/libavcodec/indeo2.c
+++ b/libavcodec/indeo2.c
@@ -136,8 +136,10 @@
 
 static int ir2_decode_frame(AVCodecContext *avctx,
                         void *data, int *data_size,
-                        const uint8_t *buf, int buf_size)
+                        AVPacket *avpkt)
 {
+    const uint8_t *buf = avpkt->data;
+    int buf_size = avpkt->size;
     Ir2Context * const s = avctx->priv_data;
     AVFrame *picture = data;
     AVFrame * const p= (AVFrame*)&s->picture;