Remove unused variable.

Originally committed as revision 25369 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/avio.c

@@ -246,7 +246,6 @@ int url_read_complete(URLContext *h, unsigned char *buf, int size)
 
 int url_write(URLContext *h, const unsigned char *buf, int size)
 {
-    int ret;
     if (!(h->flags & (URL_WRONLY | URL_RDWR)))
         return AVERROR(EIO);
     /* avoid sending too big packets */