Do not skip for lossless

BUG=aomedia:1640

Change-Id: I8db947008db88dda18cd8a3fd10a9693848d5a52

av1/encoder/rdopt.c

diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index c3b8e48..64e1e85 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -7084,7 +7084,8 @@
       av1_build_inter_predictors_sb(cm, xd, mi_row, mi_col, orig_dst, bsize);
     }
 
-    check_block_skip(cpi, bsize, x, xd, 0, num_planes - 1, &skip_txfm_sb);
+    if (!cpi->common.all_lossless)
+      check_block_skip(cpi, bsize, x, xd, 0, num_planes - 1, &skip_txfm_sb);
 
     x->skip = 0;