With chroma2x2 turn compound sub8x8 off by default

Change-Id: Ie1e45b318d5f1b53c6519d91bd3e9c11a30ec56d

av1/common/blockd.h

diff --git a/av1/common/blockd.h b/av1/common/blockd.h
index 6bbb4c5..e02d72b 100644
--- a/av1/common/blockd.h
+++ b/av1/common/blockd.h
@@ -36,7 +36,7 @@
 extern "C" {
 #endif
 
-#define SUB8X8_COMP_REF 1
+#define SUB8X8_COMP_REF (!(CONFIG_CB4X4 && CONFIG_CHROMA_2X2))
 
 #define MAX_MB_PLANE 3