av_find_stream_info: change read_size to 64bit

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

libavformat/utils.c

@@ -2733,7 +2733,8 @@ int av_find_stream_info(AVFormatContext *ic)
 
 int avformat_find_stream_info(AVFormatContext *ic, AVDictionary **options)
 {
-    int i, count, ret, read_size, j;
+    int i, count, ret, j;
+    int64_t read_size;
     AVStream *st;
     AVPacket pkt1, *pkt;
     int64_t old_offset = avio_tell(ic->pb);