Fix print time overflow.

Firmware/ultralcd.cpp

@@ -2468,10 +2468,10 @@ void lcd_menu_statistics()
 	{
 		float _met = ((float)total_filament_used) / (100000.f);
 		int _cm = (total_filament_used - (_met * 100000)) / 10;
-		int _t = (millis() - starttime) / 1000;
+		uint32_t _t = (millis() - starttime) / 1000;
 		int _h = _t / 3600;
-		int _m = (_t - (_h * 3600)) / 60;
-		int _s = _t - ((_h * 3600) + (_m * 60));
+		int _m = (_t - (_h * 3600ul)) / 60;
+		int _s = _t - ((_h * 3600ul) + (_m * 60));
 //|01234567890123456789|
 //|Filament used:      |
 //|      000m 00.000cm |