libx264: switch to ff_alloc_packet2().

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavcodec/libx264.c

@@ -101,7 +101,7 @@ static int encode_nals(AVCodecContext *ctx, AVPacket *pkt,
     for (i = 0; i < nnal; i++)
         size += nals[i].i_payload;
 
-    if ((ret = ff_alloc_packet(pkt, size)) < 0)
+    if ((ret = ff_alloc_packet2(ctx, pkt, size)) < 0)
         return ret;
 
     p = pkt->data;