Remove @deprecated notice from AVFrac, it is not deprecated anymore.

Originally committed as revision 17142 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/avformat.h

@@ -211,7 +211,6 @@ static inline void av_free_packet(AVPacket *pkt)
 /**
  * The exact value of the fractional number is: 'val + num / den'.
  * num is assumed to be 0 <= num < den.
- * @deprecated Use AVRational instead.
 */
 typedef struct AVFrac {
     int64_t val, num, den;