Fixed enum value in cluster_utils.cpp to fix build.

Author: Vaughn Betz

vpr/src/pack/cluster_util.cpp

@@ -1245,7 +1245,7 @@ enum e_block_pack_status try_place_atom_block_rec(const t_pb_graph_node* pb_grap
     } else {
        /* if this is not the first child of this parent, must match existing parent mode */
        if (parent_pb->mode != pb_graph_node->pb_type->parent_mode->index) {
-            return BLK_FAILED_FEASIBLE;
+            return e_block_pack_status::BLK_FAILED_FEASIBLE;
         }
     }