When opening a file to check its avformat, the AVFormatContext pointer was
not initialized to NULL before it was passed by reference to the open
function.

Patch by Bradley Broom <bmbroom@gmail.com>

https://bugs.gentoo.org/show_bug.cgi?id=446922

--- mediatomb-0.12.1/src/metadata/ffmpeg_handler.cc
+++ mediatomb-0.12.1/src/metadata/ffmpeg_handler.cc
@@ -281,7 +281,7 @@
     int x = 0;
     int y = 0;
 
-	AVFormatContext *pFormatCtx;
+	AVFormatContext *pFormatCtx = NULL;
 	
 	// Suppress all log messages
 	av_log_set_callback(FfmpegNoOutputStub);