Keeps segfaulting shortly after startup (when it says Wave 1)
#0 0x000055555555bf80 in vec2d_sub ()
#1 0x000055555556d89f in soldierunit_update ()
#2 0x00005555555586d1 in update ()
#3 0x00005555555593ee in gameloop_start ()
#4 0x0000555555557a0b in main ()