acelp: Remove unused gray_decode table.

libavcodec/acelp_vectors.c

@@ -93,16 +93,6 @@ const uint8_t ff_fc_4pulses_8bits_track_4[32] =
     78, 79,
 };
 
-#if 0
-static uint8_t gray_decode[32] =
-{
-    0,  1,  3,  2,  7,  6,  4,  5,
-   15, 14, 12, 13,  8,  9, 11, 10,
-   31, 30, 28, 29, 24, 25, 27, 26,
-   16, 17, 19, 18, 23, 22, 20, 21
-};
-#endif
-
 const float ff_pow_0_7[10] = {
     0.700000, 0.490000, 0.343000, 0.240100, 0.168070,
     0.117649, 0.082354, 0.057648, 0.040354, 0.028248