Revert "libvpx: Pull from upstream"

source/libvpx/vp9/encoder/vp9_mcomp.c

Index: source/libvpx/vp9/encoder/vp9_mcomp.c
diff --git a/source/libvpx/vp9/encoder/vp9_mcomp.c b/source/libvpx/vp9/encoder/vp9_mcomp.c
index 159e0fc0c712b378c2826ba79a2c85fb91a515fb..a428f1a2d3228836accb9b811725ccaeba4dcc63 100644
--- a/source/libvpx/vp9/encoder/vp9_mcomp.c
+++ b/source/libvpx/vp9/encoder/vp9_mcomp.c
@@ -90,10 +90,13 @@ static int mv_err_cost(const MV *mv, const MV *ref,
 
 static int mvsad_err_cost(const MACROBLOCK *x, const MV *mv, const MV *ref,
                           int error_per_bit) {
-  const MV diff = { mv->row - ref->row,
-                    mv->col - ref->col };
-  return ROUND_POWER_OF_TWO(mv_cost(&diff, x->nmvjointsadcost,
-                                    x->nmvsadcost) * error_per_bit, 8);
+  if (x->nmvsadcost) {
+    const MV diff = { mv->row - ref->row,
+                      mv->col - ref->col };
+    return ROUND_POWER_OF_TWO(mv_cost(&diff, x->nmvjointsadcost,
+                                      x->nmvsadcost) * error_per_bit, 8);
+  }
+  return 0;
 }
 
 void vp9_init_dsmotion_compensation(search_site_config *cfg, int stride) {