Print timer now stops when it sees the last extruder temperature being shutdown

Marlin/temperature.cpp

@@ -1111,6 +1111,9 @@ void disable_all_heaters() {
   for (int i = 0; i < EXTRUDERS; i++) setTargetHotend(0, i);
   setTargetBed(0);
 
+  // If all heaters go down then for sure our print job has stopped
+  if( print_job_start_ms != 0 ) print_job_stop_ms = millis();
+
   #define DISABLE_HEATER(NR) { \
     target_temperature[NR] = 0; \
     soft_pwm[NR] = 0; \