Facilitate multi-threading in loop restoration

Copy and sync functions have been added to facilitate
multi-threading in loop restoration.

Change-Id: I4b45f9671c8b4e2add3038670096c32f1a4e032d
diff --git a/av1/encoder/pickrst.c b/av1/encoder/pickrst.c
index d3a1b74..0dbc489 100644
--- a/av1/encoder/pickrst.c
+++ b/av1/encoder/pickrst.c
@@ -1243,7 +1243,7 @@
   };
 
   reset_rsc(rsc);
-  rsc_on_tile(0, 0, rsc);
+  rsc_on_tile(LR_TILE_ROW, LR_TILE_COL, rsc);
   av1_foreach_rest_unit_in_plane(rsc->cm, rsc->plane, funs[rtype], rsc,
                                  &rsc->tile_rect, rsc->cm->rst_tmpbuf, NULL);
   return RDCOST_DBL(rsc->x->rdmult, rsc->bits >> 4, rsc->sse);