avformat_alloc_context: initialize raw_packet_buffer_remaining_size.

This currently works for most users because
avformat_open_input sets it, but this patch fixes any
applications not using that function.
Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

libavformat/options.c

@@ -117,6 +117,7 @@ AVFormatContext *avformat_alloc_context(void)
         return NULL;
     }
     ic->internal->offset = AV_NOPTS_VALUE;
+    ic->internal->raw_packet_buffer_remaining_size = RAW_PACKET_BUFFER_SIZE;
 
     return ic;
 }