Update joint_cdf table once per frame.

Move computing the joint_cdf table per coded mv joint symbol to
 computing it only when the probabilities are updated.

Change-Id: If5d195f70e6fad7b60f69606c8386ad5e69657d2
diff --git a/av1/encoder/encodemv.c b/av1/encoder/encodemv.c
index 7276fee..5385d6b 100644
--- a/av1/encoder/encodemv.c
+++ b/av1/encoder/encodemv.c
@@ -239,7 +239,11 @@
 #if CONFIG_REF_MV
   (void)is_compound;
 #endif
+#if CONFIG_DAALA_EC
+  aom_write_symbol(w, j, mvctx->joint_cdf, MV_JOINTS);
+#else
   av1_write_token(w, av1_mv_joint_tree, mvctx->joints, &mv_joint_encodings[j]);
+#endif
   if (mv_joint_vertical(j))
     encode_mv_component(w, diff.row, &mvctx->comps[0], usehp);