Set cur_frame_force_integer_mv in MACROBLOCKD

The current code sets this in encode_sb_row(). But in case of
row-mt, the 'xd' instance in encode_sb_row() and the 'xd' instance
in write_tile_obut() are different. So to get the right behavior,
we would have to set the value here as well.

This fixes a bug where row-mt produces invalid bitstream sometimes.

BUG=aomedia:3325

Change-Id: Ibeb8d507c985d5e2ce6059eeb6d3202bdb57161a

av1/encoder/encoder.c

diff --git a/av1/encoder/encoder.c b/av1/encoder/encoder.c
index 156febf..c3c7345 100644
--- a/av1/encoder/encoder.c
+++ b/av1/encoder/encoder.c
@@ -3553,6 +3553,11 @@
     cpi->common.features.cur_frame_force_integer_mv = 0;
   }
 
+  // This is used by av1_pack_bitstream. So this needs to be set in case of
+  // row-mt where the encoding code will use a temporary structure.
+  cpi->td.mb.e_mbd.cur_frame_force_integer_mv =
+      cpi->common.features.cur_frame_force_integer_mv;
+
   // Set default state for segment based loop filter update flags.
   cm->lf.mode_ref_delta_update = 0;