Clean-up selective_ref_gm speed feature

The speed feature selective_ref_gm was
unused, and is cleaned up.

Change-Id: I819c9163d35d280d72124b48fcc4dd23dbc1b3ca

av1/encoder/global_motion_facade.c

diff --git a/av1/encoder/global_motion_facade.c b/av1/encoder/global_motion_facade.c
index c5a7415..31c69da 100644
--- a/av1/encoder/global_motion_facade.c
+++ b/av1/encoder/global_motion_facade.c
@@ -258,19 +258,6 @@
   return 0;
 }
 
-// Function to decide if we can skip the global motion parameter computation
-// for a particular ref frame.
-static AOM_INLINE int skip_gm_frame(AV1_COMMON *const cm, int ref_frame) {
-  if ((ref_frame == LAST3_FRAME || ref_frame == LAST2_FRAME) &&
-      cm->global_motion[GOLDEN_FRAME].wmtype != IDENTITY) {
-    return get_relative_dist(
-               &cm->seq_params.order_hint_info,
-               cm->cur_frame->ref_order_hints[ref_frame - LAST_FRAME],
-               cm->cur_frame->ref_order_hints[GOLDEN_FRAME - LAST_FRAME]) <= 0;
-  }
-  return 0;
-}
-
 // Prunes reference frames for global motion estimation based on the speed
 // feature 'gm_search_type'.
 static int do_gm_search_logic(SPEED_FEATURES *const sf, int frame) {
@@ -323,8 +310,7 @@
 
     if (ref_buf[frame]->y_crop_width == cpi->source->y_crop_width &&
         ref_buf[frame]->y_crop_height == cpi->source->y_crop_height &&
-        do_gm_search_logic(&cpi->sf, frame) && !prune_ref_frames &&
-        !(cpi->sf.gm_sf.selective_ref_gm && skip_gm_frame(cm, frame))) {
+        do_gm_search_logic(&cpi->sf, frame) && !prune_ref_frames) {
       assert(ref_buf[frame] != NULL);
       const int relative_frame_dist = av1_encoder_get_relative_dist(
           buf->display_order_hint, cm->cur_frame->display_order_hint);

av1/encoder/speed_features.c

diff --git a/av1/encoder/speed_features.c b/av1/encoder/speed_features.c
index c78bbd7..feebc0f 100644
--- a/av1/encoder/speed_features.c
+++ b/av1/encoder/speed_features.c
@@ -1064,7 +1064,6 @@
 }
 
 static AOM_INLINE void init_gm_sf(GLOBAL_MOTION_SPEED_FEATURES *gm_sf) {
-  gm_sf->selective_ref_gm = 1;
   gm_sf->gm_search_type = GM_FULL_SEARCH;
   gm_sf->prune_ref_frame_for_gm_search = 0;
 }

av1/encoder/speed_features.h

diff --git a/av1/encoder/speed_features.h b/av1/encoder/speed_features.h
index c1fc124..67c9019 100644
--- a/av1/encoder/speed_features.h
+++ b/av1/encoder/speed_features.h
@@ -377,11 +377,6 @@
 } TPL_SPEED_FEATURES;
 
 typedef struct GLOBAL_MOTION_SPEED_FEATURES {
-  // Do not compute the global motion parameters for a LAST2_FRAME or
-  // LAST3_FRAME if the GOLDEN_FRAME is closer and it has a non identity
-  // global model.
-  int selective_ref_gm;
-
   GM_SEARCH_TYPE gm_search_type;
 
   // During global motion estimation, prune remaining reference frames in a