lavf,lavd: replace av_new_stream->avformat_new_stream part I.

Trivial replacements with sed are done in this commit:
sed 's/av_new_stream(\([^)]*\), 0)/avformat_new_stream(\1, NULL)/'

libavformat/output-example.c

@@ -200,7 +200,7 @@ static AVStream *add_video_stream(AVFormatContext *oc, enum CodecID codec_id)
     AVCodecContext *c;
     AVStream *st;
 
-    st = av_new_stream(oc, 0);
+    st = avformat_new_stream(oc, NULL);
     if (!st) {
         fprintf(stderr, "Could not alloc stream\n");
         exit(1);