Make ref-mv experiment support ActiveMap

Reset the ref_mv_idx and predicted motion vector when the coding
block belongs to skip segment.

Change-Id: I5746ab315a436b829b64a1a25121989d3c11c995

vp10/encoder/rdopt.c

@@ -9925,6 +9925,10 @@ void vp10_rd_pick_inter_mode_sb_seg_skip(VP10_COMP *cpi,
   mbmi->ref_frame[0] = LAST_FRAME;
   mbmi->ref_frame[1] = NONE;
   mbmi->mv[0].as_int = 0;
+#if CONFIG_REF_MV
+  mbmi->ref_mv_idx = 0;
+  mbmi->pred_mv[0].as_int = 0;
+#endif
   x->skip = 1;
 
   if (cm->interp_filter != BILINEAR) {