[0.17.9] Train out of fuel alerts only for primary locomotive

[lava84flow]

When using a Double-Headed Automatic Train, the new map alert for "Train without fuel" only works when the 'default' head is out of gas and actively trying to pull it. If the 'non-default' head is out of gas and trying to pull the train, there is no alert.

The default head is the one that is highlighted in the Train GUI when you click on the non-locomotive sections of the train.