Remove useless variable since r8456.

Originally committed as revision 12493 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/cookdata.h

@@ -40,8 +40,6 @@ static const float dither_tab[8] = {
   0.0, 0.0, 0.0, 0.0, 0.0, 0.176777, 0.25, 0.707107,
 };
 
-static const float randsign[2] = {1.0, -1.0};
-
 static const float quant_centroid_tab[7][14] = {
   { 0.000, 0.392, 0.761, 1.120, 1.477, 1.832, 2.183, 2.541, 2.893, 3.245, 3.598, 3.942, 4.288, 4.724 },
   { 0.000, 0.544, 1.060, 1.563, 2.068, 2.571, 3.072, 3.562, 4.070, 4.620, 0.000, 0.000, 0.000, 0.000 },