cb4x4: Elide special cases cb4x4 doesn't need

These conditions in has_top_right() are never true when cb4x4 is
enabled.

The corresponding check in has_bottom_left() is already behind a
similar #if.

This is needed by a subsequent patch to move sub-4x4 block sizes
behind their own configuration flag, since that changes the value
of bw_unit, which might cause the condition to become true when it
should not be.

Encoder and decoder output should remain unchanged.

Change-Id: I648654dfc265f911d83668d94dc927ebc0c70771

av1/common/reconintra.c

diff --git a/av1/common/reconintra.c b/av1/common/reconintra.c
index c9b7edb..b8cb2ff 100644
--- a/av1/common/reconintra.c
+++ b/av1/common/reconintra.c
@@ -447,8 +447,10 @@
   const int plane_bw_unit = AOMMAX(bw_unit >> ss_x, 1);
   const int top_right_count_unit = tx_size_wide_unit[txsz];
 
+#if !CONFIG_CB4X4
   // Special handling for block sizes 4x8 and 4x4.
   if (ss_x == 0 && bw_unit < 2 && col_off == 0) return 1;
+#endif
 
   if (row_off > 0) {  // Just need to check if enough pixels on the right.
     return col_off + top_right_count_unit < plane_bw_unit;