we use net->vio in my_net_local_init, but in the my_net_init
implementation we set it after the call, so work with unspecified
net->vio value


sql/net_serv.cc:
  Bug #29117 (init_file test crashes with embedded server)
  
  as we started using net->vio in my_net_local_init, we should set
  it before the call