Avoid crash due to ic being NULL if avformat_open_input fails.

This updates the code to match current master.
Should fix trac issue #410.

Signed-off-by: Reimar Döffinger <Reimar.Doeffinger@gmx.de>

libavformat/utils.c

@@ -537,7 +537,8 @@ int av_open_input_stream(AVFormatContext **ic_ptr,
     else
         ic->pb = pb;
 
-    err = avformat_open_input(&ic, filename, fmt, &opts);
+    if ((err = avformat_open_input(&ic, filename, fmt, &opts)) < 0)
+        goto fail;
 
     *ic_ptr = ic;
     ic->pb = ic->pb ? ic->pb : pb; // don't leak custom pb if it wasn't set above