Update server_functions.sqf

This will fix the notorious error you get in the server log, when adding DZAI or Sarge variable exceptions there.
I mean this error here:

Error in expression <) && (vehicle _x getVariable ["DZAI",0] != 1) && !((typeOf vehicle _x) in DZE_sa>
Error position: <!= 1) && !((typeOf vehicle _x) in DZE_sa>
Error Generic error in expression