Remove dead assignments found by CSA

Originally committed as revision 18733 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/qtrleenc.c

@@ -200,7 +200,6 @@ static void qtrle_encode_line(QtrleEncContext *s, AVFrame *p, int line, uint8_t
 
     i=0;
     this_line = p->               data[0] + line*p->linesize[0];
-    prev_line = s->previous_frame.data[0] + line*p->linesize[0];
 
     if (s->rlecode_table[0] == 0) {
         bytestream_put_byte(buf, s->skip_table[0] + 1);

libavcodec/sp5xdec.c

@@ -41,7 +41,7 @@ static int sp5x_decode_frame(AVCodecContext *avctx,
     MJpegDecodeContext *s = avctx->priv_data;
 #endif
     const int qscale = 5;
-    const uint8_t *buf_ptr, *buf_end;
+    const uint8_t *buf_ptr;
     uint8_t *recoded;
     int i = 0, j = 0;
 
@@ -49,7 +49,6 @@ static int sp5x_decode_frame(AVCodecContext *avctx,
         return -1;
 
     buf_ptr = buf;
-    buf_end = buf + buf_size;
 
 #if 1
     recoded = av_mallocz(buf_size + 1024);

libavformat/mtv.c

@@ -133,8 +133,6 @@ static int mtv_read_packet(AVFormatContext *s, AVPacket *pkt)
     int i;
 #endif
 
-    ret = 0;
-
     if((url_ftell(pb) - s->data_offset + mtv->img_segment_size) % mtv->full_segment_size)
     {
         url_fskip(pb, MTV_AUDIO_PADDING_SIZE);