ref-mv: Don't stop scanning when ref-mv stack is full.

This would result in certain motion vectors getting
lower weights than they deserve, so putting them in
the wrong position in the stack.

BUG=aomedia:981

Change-Id: I8bd106e97f494f5d3debaf967efcabcd39846726

av1/common/mvref_common.c

@@ -133,7 +133,7 @@ static uint8_t add_ref_mv_candidate(
         if (index < *refmv_count) ref_mv_stack[index].weight += weight * len;
 
         // Add a new item to the list.
-        if (index == *refmv_count) {
+        if (index == *refmv_count && *refmv_count < MAX_REF_MV_STACK_SIZE) {
           ref_mv_stack[index].this_mv = this_refmv;
           ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
               get_sub_block_pred_mv(candidate_mi, ref, col, block), this_refmv);
@@ -171,7 +171,7 @@ static uint8_t add_ref_mv_candidate(
       if (index < *refmv_count) ref_mv_stack[index].weight += weight * len;
 
       // Add a new item to the list.
-      if (index == *refmv_count) {
+      if (index == *refmv_count && *refmv_count < MAX_REF_MV_STACK_SIZE) {
         ref_mv_stack[index].this_mv = this_refmv[0];
         ref_mv_stack[index].comp_mv = this_refmv[1];
         ref_mv_stack[index].pred_diff[0] = av1_get_pred_diff_ctx(
@@ -211,7 +211,7 @@ static uint8_t scan_row_mbmi(const AV1_COMMON *cm, const MACROBLOCKD *xd,
   const int use_step_16 = (xd->n8_w >= 16);
   MODE_INFO **const candidate_mi0 = xd->mi + row_offset * xd->mi_stride;
 
-  for (i = 0; i < end_mi && *refmv_count < MAX_REF_MV_STACK_SIZE;) {
+  for (i = 0; i < end_mi;) {
     const MODE_INFO *const candidate_mi = candidate_mi0[col_offset + i];
     const MB_MODE_INFO *const candidate = &candidate_mi->mbmi;
     const int candidate_bsize = candidate->sb_type;
@@ -280,7 +280,7 @@ static uint8_t scan_col_mbmi(const AV1_COMMON *cm, const MACROBLOCKD *xd,
   }
   const int use_step_16 = (xd->n8_h >= 16);
 
-  for (i = 0; i < end_mi && *refmv_count < MAX_REF_MV_STACK_SIZE;) {
+  for (i = 0; i < end_mi;) {
     const MODE_INFO *const candidate_mi =
         xd->mi[(row_offset + i) * xd->mi_stride + col_offset];
     const MB_MODE_INFO *const candidate = &candidate_mi->mbmi;
@@ -343,8 +343,7 @@ static uint8_t scan_blk_mbmi(const AV1_COMMON *cm, const MACROBLOCKD *xd,
   mi_pos.row = row_offset;
   mi_pos.col = col_offset;
 
-  if (is_inside(tile, mi_col, mi_row, cm->mi_rows, cm, &mi_pos) &&
-      *refmv_count < MAX_REF_MV_STACK_SIZE) {
+  if (is_inside(tile, mi_col, mi_row, cm->mi_rows, cm, &mi_pos)) {
     const MODE_INFO *const candidate_mi =
         xd->mi[mi_pos.row * xd->mi_stride + mi_pos.col];
     const MB_MODE_INFO *const candidate = &candidate_mi->mbmi;