Extend DISABLE_TRELLISQ_SEARCH to include calls from var-tx

Currently, trellis optimization is performed in
av1_tx_block_rd_b when var-tx is enabled even when DISABLE_TRELLISQ_SEARCH
is set to 1.

The drop in performance when DISABLE_TRELLISQ_SEARCH is set to 1 is
1.8% on lowres

Change-Id: I89e26d4d4f57944db11b528d0e10048ae650d8a1

av1/encoder/rdopt.c

@@ -4199,10 +4199,16 @@ void av1_tx_block_rd_b(const AV1_COMP *cpi, MACROBLOCK *x, TX_SIZE tx_size,
   return;
 #endif
 
+#if DISABLE_TRELLISQ_SEARCH
+  av1_xform_quant(cm, x, plane, block, blk_row, blk_col, plane_bsize, tx_size,
+                  coeff_ctx, AV1_XFORM_QUANT_B);
+
+#else
   av1_xform_quant(cm, x, plane, block, blk_row, blk_col, plane_bsize, tx_size,
                   coeff_ctx, AV1_XFORM_QUANT_FP);
 
   av1_optimize_b(cm, x, plane, block, plane_bsize, tx_size, a, l);
+#endif  // DISABLE_TRELLISQ_SEARCH
 
 // TODO(any): Use av1_dist_block to compute distortion
 #if CONFIG_HIGHBITDEPTH