Remove macroblock::skip_optimize.

This is not used since the commint 00cd5de5,
"Remove skip_recode speed feature".

Change-Id: Ic03da6c0095f6285a3889d5d22e8aaa2e6cbfd79

av1/encoder/block.h

@@ -81,7 +81,6 @@ struct macroblock {
   MB_MODE_INFO_EXT *mbmi_ext;
   int skip_block;
   int select_tx_size;
-  int skip_optimize;
   int q_index;
 
   // The equivalent error at the current rdmult of one whole bit (not one

av1/encoder/encodeframe.c

@@ -2175,7 +2175,6 @@ static void encode_sb(AV1_COMP *cpi, ThreadData *td, const TileInfo *const tile,
 
       if (!x->skip) {
         int this_rate = 0;
-        x->skip_optimize = 0;
         x->use_lp32x32fdct = cpi->sf.use_lp32x32fdct;
 
         av1_encode_sb_supertx(x, bsize);
@@ -5019,7 +5018,6 @@ static void encode_superblock(AV1_COMP *cpi, ThreadData *td, TOKENEXTRA **t,
   const int mi_width = num_8x8_blocks_wide_lookup[bsize];
   const int mi_height = num_8x8_blocks_high_lookup[bsize];
 
-  x->skip_optimize = ctx->is_coded;
   ctx->is_coded = 1;
   x->use_lp32x32fdct = cpi->sf.use_lp32x32fdct;