Include partition cost in best_remain_rdcost for PARTITION_HORZ

Currently, the calculation of best_remain_rdcost for PARTITION_HORZ does
not take the cost of choosing PARTITION_HORZ into account. This commit
corrects this issue and make it consistent with the calculation for
other PARTITION_TYPES.

STATS_CHANGED

Change-Id: Ibca173739b2a6de269955ebe9c54b39cb26f0895

av1/encoder/encodeframe.c

diff --git a/av1/encoder/encodeframe.c b/av1/encoder/encodeframe.c
index 7cf3247..f06cf25 100644
--- a/av1/encoder/encodeframe.c
+++ b/av1/encoder/encodeframe.c
@@ -4398,11 +4398,11 @@
       pc_tree->horizontal[0].pred_interp_filter =
           av1_extract_interp_filter(ctx_none->mic.interp_filters, 0);
     }
+    sum_rdc.rate = partition_cost[PARTITION_HORZ];
+    sum_rdc.rdcost = RDCOST(x->rdmult, sum_rdc.rate, 0);
     const int64_t best_remain_rdcost = best_rdc.rdcost == INT64_MAX
                                            ? INT64_MAX
                                            : (best_rdc.rdcost - sum_rdc.rdcost);
-    sum_rdc.rate = partition_cost[PARTITION_HORZ];
-    sum_rdc.rdcost = RDCOST(x->rdmult, sum_rdc.rate, 0);
     rd_pick_sb_modes(cpi, tile_data, x, mi_row, mi_col, &this_rdc,
                      PARTITION_HORZ, subsize, &pc_tree->horizontal[0],
                      best_remain_rdcost);