Disable extended compound modes in speed 6

The extended compound modes NEAREST_NEWMV, NEW_NEARESTMV,
NEAR_NEWMV, NEW_NEARMV are disabled in speed 6.

cpu-used  Instruction Count     BD-Rate Loss(%)
           Reduction(%)     avg.psnr  ovr.psnr  ssim
   6          1.3           0.1824    0.1858	0.084

STATS_CHANGED

Change-Id: I523acfe8a62b0d17978d79ccdb2b064a67837f47
diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index 900f1e3..65a97e1 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -4516,6 +4516,8 @@
       this_mode == NEW_NEWMV || this_mode == GLOBAL_GLOBALMV)
     return 0;
 
+  if (prune_compound_using_neighbors >= 3) return 1;
+
   int is_ref_match[2] = { 0 };  // 0 - match for forward refs
                                 // 1 - match for backward refs
   // Check if ref frames of this block matches with left neighbor.
diff --git a/av1/encoder/speed_features.c b/av1/encoder/speed_features.c
index ecd96a3..ae3c6d8 100644
--- a/av1/encoder/speed_features.c
+++ b/av1/encoder/speed_features.c
@@ -1076,6 +1076,7 @@
     sf->inter_sf.prune_inter_modes_based_on_tpl = boosted ? 0 : 3;
     sf->inter_sf.prune_nearmv_using_neighbors = 1;
     sf->inter_sf.selective_ref_frame = 6;
+    sf->inter_sf.prune_compound_using_neighbors = 3;
 
     sf->intra_sf.chroma_intra_pruning_with_hog = 4;
     sf->intra_sf.intra_pruning_with_hog = 4;