Clean up resources in DRC.

src/drc/drc/built-in-macros/drc.lym

@@ -4717,8 +4717,12 @@ CODE
       @output_layout_file = nil
       @output_cell = nil
       @output_rdb_file = nil
+      @output_rdb_cell = nil
       @output_rdb = nil
       @output_rdb_index = nil
+
+      # clean up temp data
+      @dss && @dss._destroy
       
       if final && @log_file
         @log_file.close