Change ret type to int64_t because url_fseek returns int64_t.

This fixes seeking in files > 2gb.
Patch by Sean Soria, sean dot soria at gmail dot com.

Originally committed as revision 20693 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/utils.c

@@ -1513,7 +1513,8 @@ static int av_seek_frame_byte(AVFormatContext *s, int stream_index, int64_t pos,
 static int av_seek_frame_generic(AVFormatContext *s,
                                  int stream_index, int64_t timestamp, int flags)
 {
-    int index, ret;
+    int index;
+    int64_t ret;
     AVStream *st;
     AVIndexEntry *ie;