Remove unused variables, fixes the following warnings:

siff.c:187: warning: unused variable 'snddata'
siff.c:186: warning: unused variable 'size2'

Originally committed as revision 10884 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavformat/siff.c

@@ -183,8 +183,7 @@ static int siff_read_header(AVFormatContext *s, AVFormatParameters *ap)
 static int siff_read_packet(AVFormatContext *s, AVPacket *pkt)
 {
     SIFFContext *c = s->priv_data;
-    int size, size2;
-    uint8_t *snddata;
+    int size;
 
     if (c->has_video){
         if (c->cur_frame >= c->frames)