lavf: revert commit bb99ae3a

	Author: Michael Niedermayer <michaelni@gmx.at>
	Date:   Thu Nov 3 22:38:10 2011 +0100

	    lavf: fix null pointer dereference in rdt
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

This is no longer needed and causes various problems with RTSP
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

libavformat/utils.c

@@ -634,9 +634,6 @@ static int init_input(AVFormatContext *s, const char *filename, AVDictionary **o
     int ret;
     AVProbeData pd = {filename, NULL, 0};
 
-    if(s->iformat && !strlen(filename))
-        return 0;
-
     if (s->pb) {
         s->flags |= AVFMT_FLAG_CUSTOM_IO;
         if (!s->iformat)