rtc: Fix to set segment_id for variance partition

segment_id for the current superblock was not
being set before entering variance_partition.
This affects the variance thresholds, in particular
for speed 9.

bdrate gains on rtc set for speed 9:
avg gain ~2.2%, max gain ~9%, max loss ~1.4

Neutral to small gains on rtc_derf, and for speed 7,8.
Negligible speed change.

Change-Id: I785100ecaf95db3a5703545603e8ec1f3d583def
diff --git a/av1/encoder/encodeframe.c b/av1/encoder/encodeframe.c
index 916b1b8..63aec92 100644
--- a/av1/encoder/encodeframe.c
+++ b/av1/encoder/encodeframe.c
@@ -547,8 +547,7 @@
     av1_set_fixed_partitioning(cpi, tile_info, mi, mi_row, mi_col, bsize);
   } else if (sf->part_sf.partition_search_type == VAR_BASED_PARTITION) {
     // set a variance-based partition
-    av1_set_offsets_without_segment_id(cpi, tile_info, x, mi_row, mi_col,
-                                       sb_size);
+    av1_set_offsets(cpi, tile_info, x, mi_row, mi_col, sb_size);
     av1_choose_var_based_partitioning(cpi, tile_info, td, x, mi_row, mi_col);
   }
   assert(sf->part_sf.partition_search_type == FIXED_PARTITION || seg_skip ||