Skip tx_size count in lossless mode

Resolve an enc/dec mismatch issue when segmentation is in use.

BUG=aomedia:131

Change-Id: Id93dfc1b0d99a1cccc8c8408f9fb0dfcf83f0a7c

av1/encoder/encodeframe.c

@@ -5748,7 +5748,7 @@ static void encode_superblock(const AV1_COMP *const cpi, ThreadData *td,
 #else
     TX_SIZE tx_size = mbmi->tx_size;
 #endif
-    if (cm->tx_mode == TX_MODE_SELECT &&
+    if (cm->tx_mode == TX_MODE_SELECT && !xd->lossless[mbmi->segment_id] &&
 #if CONFIG_CB4X4 && (CONFIG_VAR_TX || CONFIG_RECT_TX)
 #if CONFIG_RECT_TX
         mbmi->sb_type > BLOCK_4X4 &&