The source you provided makes clear that sieges are lawful provided non-combatants aren’t affected (so starving civilians, barring humanitarian aid, etc. makes a siege unlawful). Furthermore, it states that sieges where non-combatants are affected were lawful prior to the 20th century.
In the context of ATLA, there’s not really enough known about the geopolitics of the world to properly gauge whether or not besieging a city is a war crime. The frequency of sieges in the show (North Pole, Ba Sing Se) can’t be used as an argument for their legality since they’re undertaken by a state that is known for mistreating prisoners of war, disrespecting geopolitical boundaries, and so on. Regardless, you can’t judge the Avatar universe by real world law.
YOUR_VARIABLE=1 %command%
In Steam launch options for a specific game.
So, in this case:
RADV_PERFTEST=nggc %command%