Auj. is short for “Aujourd’hui“. It means the town changed its name since he was born.

Birth : Circa 1645 in St-Etienne De Mortagne, now Mortagne-Sur-Gironde

Ar. is short for “Arrondissement“, Saintes is an arrondissement of the Charentes-Maritimes department.

I’m not exactly sure what ev. means, but it’s probably short for the region name before arrondissement were adopted in 1800.

So the current location is:

Mortagne-Sur-Gironde, Arrondissement Saintes, Charente-Maritime

However it’s not a full adress, it’s just the city. It’s kind of like saying “Houston, Texas”, the last part indicating the region, except it’s not very useful because in France there are (almost) no two cities with the same name where you’d need to add the region to be unambiguous.

Hope that helps!