Fix RDO issue of obmc + speed feature fast_inter_tx_type_search

Change-Id: I86a967ad2d824ca7877626eed9eb11f0e057b22d
diff --git a/vp10/encoder/rdopt.c b/vp10/encoder/rdopt.c
index 80132a1..7021cb2 100644
--- a/vp10/encoder/rdopt.c
+++ b/vp10/encoder/rdopt.c
@@ -9668,6 +9668,12 @@
 
     if (is_inter_mode(mbmi->mode)) {
       vp10_build_inter_predictors_sb(xd, mi_row, mi_col, bsize);
+#if CONFIG_OBMC
+      if (mbmi->motion_variation == OBMC_CAUSAL)
+        vp10_build_obmc_inter_prediction(cm, xd, mi_row, mi_col, 0, NULL, NULL,
+                                         dst_buf1, dst_stride1,
+                                         dst_buf2, dst_stride2);
+#endif  // CONFIG_OBMC
       vp10_subtract_plane(x, bsize, 0);
 #if CONFIG_VAR_TX
       if (cm->tx_mode == TX_MODE_SELECT || xd->lossless[mbmi->segment_id]) {