JNT_COMP: 4. add context and entropy read/write

Change-Id: I0e6f7ab981e31f7120105515f6204568b6dc82d3
diff --git a/av1/common/enums.h b/av1/common/enums.h
index 70c90da..2a3368a 100644
--- a/av1/common/enums.h
+++ b/av1/common/enums.h
@@ -640,6 +640,10 @@
 
 #define SKIP_CONTEXTS 3
 
+#if CONFIG_JNT_COMP
+#define COMP_INDEX_CONTEXTS 9
+#endif  // CONFIG_JNT_COMP
+
 #define NMV_CONTEXTS 3
 
 #define NEWMV_MODE_CONTEXTS 7