All (proper) Airlines have a simple solution for that, they just turn off GPS. Most of the time the ADIRS/ADIRU (bit too much to explain what it is here, the Wiki article is pretty good) does it automatically as well.
For those interested, here’s a Video where GPS gets jammed and there’s an explanation on what they do and what happens, when it gets spoofed www.youtube.com/watch?v=4dG_Whxzdkk