Added encryption simulation in dbsim

Option --encryption=1 enables encryption simulation in dbsim. The
`do_crypt()` callback flips bits of input buffer and writes to output.

dbsim/db_server_service.hpp

@@ -65,7 +65,6 @@ namespace db
                      void*                 output,
                      bool                  encrypt,
                      bool                  last) override;
-                     
     private:
         db::server& server_;
     };