Fix an enc/dec mismatch issue in rect-tx

This commit resolves a rare enc/dec mismatch issue due to the
intracacy of using rectangular transform block size for intra
coded blocks.

BUG=aomedia:562

Change-Id: I10c52339a995a89bafa3a3330469ee3f2b784768

av1/encoder/encodeframe.c

@@ -6077,7 +6077,7 @@ static void encode_superblock(const AV1_COMP *const cpi, ThreadData *td,
         const TX_SIZE coded_tx_size = txsize_sqr_up_map[tx_size];
         const int depth = tx_size_to_depth(coded_tx_size);
         ++td->counts->tx_size[tx_size_cat][tx_size_ctx][depth];
-        if (tx_size != max_txsize_lookup[bsize]) ++x->txb_split_count;
+        if (tx_size != max_txsize_rect_lookup[bsize]) ++x->txb_split_count;
       }
 #else
       const int tx_size_ctx = get_tx_size_context(xd);