Rewrite an operation to avoid integer out-of-range

Fix ubsan warning of the left shift operation.

Change-Id: Ib01b6ecd4a4e142948b53792a2d34153cc85784a

av1/encoder/rdopt.c

diff --git a/av1/encoder/rdopt.c b/av1/encoder/rdopt.c
index e53a135..38e65e4 100644
--- a/av1/encoder/rdopt.c
+++ b/av1/encoder/rdopt.c
@@ -9933,7 +9933,7 @@
   if (sf->adaptive_mode_search) {
     if (cm->show_frame && !cpi->rc.is_src_frame_alt_ref &&
         cpi->rc.frames_since_golden >= 3)
-      if (x->pred_mv_sad[GOLDEN_FRAME] > (x->pred_mv_sad[LAST_FRAME] << 1))
+      if ((x->pred_mv_sad[GOLDEN_FRAME] >> 1) > x->pred_mv_sad[LAST_FRAME])
         mode_skip_mask[GOLDEN_FRAME] |= INTER_ALL;
   }