cb4x4: Move sub-4X4 block sizes behind chroma flags.

cb4x4 itself should not require these sizes.

This simplifies compatibility with other experiments, since we can
first make them work with cb4x4 (which is now on by default), and
then worry about chroma_sub8x8 and chroma_2x2 (which is not) in
separate steps.

Encoder and decoder output should remain unchanged.

Change-Id: Iff2a5494cab3b7d96f881e8bd9cd4bf18c817cfa
diff --git a/examples/inspect.c b/examples/inspect.c
index 90c2c29..eadbba8 100644
--- a/examples/inspect.c
+++ b/examples/inspect.c
@@ -138,7 +138,7 @@
                                LAST_ENUM };
 
 const map_entry block_size_map[] = {
-#if CONFIG_CB4X4
+#if CONFIG_CHROMA_2X2 || CONFIG_CHROMA_SUB8X8
   ENUM(BLOCK_2X2),    ENUM(BLOCK_2X4),    ENUM(BLOCK_4X2),
 #endif
   ENUM(BLOCK_4X4),    ENUM(BLOCK_4X8),    ENUM(BLOCK_8X4),