remove no more needed fields in GIFContext, patch by Daniel Verkamp, daniel at drv dot nu

Originally committed as revision 17096 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/gif.c

@@ -139,8 +139,6 @@ static int gif_image_write_image(uint8_t **bytestream,
 }
 
 typedef struct {
-    int64_t time, file_time;
-    uint8_t buffer[100]; /* data chunks */
     AVFrame picture;
 } GIFContext;