fixed failing build on the core (missing #ifdef multithreading)(
fixed failing build on the core (missing #ifdef multithreading)(


BrewPi/firmware,BrewPi/firmware,BrewPi/firmware,glibersat/firmware,glibersat/firmware,glibersat/firmware,glibersat/firmware,BrewPi/firmware,BrewPi/firmware,glibersat/firmware,glibersat/firmware,glibersat/firmware,BrewPi/firmware,BrewPi/firmware,BrewPi/firmware