Extend inter rd model to rectangular block

Also set the threshold from 0.9 to 0.85

The following test are conducted on speed 0.

Encoding Time Reduction
city_4cif     10.77%
soccer_4cif    9.85%
crowd_run      2.86%
Keiba_832x480 11.85%
avg            8.83%

Coding Performance Change
lowres: 0.034%
midres: 0.051%

STATS_CHANGED

Change-Id: Iccfaf20874f6eee737227baf3dc5006c13c7dcba

av1/encoder/rdopt.c

diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index 9198133..759775c 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -747,10 +747,11 @@
 
 #if CONFIG_COLLECT_INTER_MODE_RD_STATS
 static int inter_mode_data_block_idx(BLOCK_SIZE bsize) {
-  if (bsize == BLOCK_8X8) return 1;
-  if (bsize == BLOCK_16X16) return 2;
-  if (bsize == BLOCK_32X32) return 3;
-  return -1;
+  if (bsize == BLOCK_4X4 || bsize == BLOCK_4X8 || bsize == BLOCK_8X4 ||
+      bsize == BLOCK_4X16 || bsize == BLOCK_16X4) {
+    return -1;
+  }
+  return 1;
 }
 
 void av1_inter_mode_data_init(TileDataEnc *tile_data) {
@@ -861,7 +862,7 @@
     rd_model->dist_sum += dist;
     rd_model->ld_sum += ld;
     rd_model->sse_sum += sse;
-    rd_model->sse_sse_sum += sse * sse;
+    rd_model->sse_sse_sum += (double)sse * (double)sse;
     rd_model->sse_ld_sum += sse * ld;
   }
 }
@@ -12189,7 +12190,7 @@
       const int data_idx = inter_modes_info->rd_idx_pair_arr[j].idx;
       *mbmi = inter_modes_info->mbmi_arr[data_idx];
       int64_t curr_est_rd = inter_modes_info->est_rd_arr[data_idx];
-      if (curr_est_rd * 0.9 > top_est_rd) {
+      if (curr_est_rd * 0.85 > top_est_rd) {
         continue;
       }
       const int mode_rate = inter_modes_info->mode_rate_arr[data_idx];