examples: fix compilation with -prod

examples/game_of_life/modules/automaton/automaton.v

@@ -23,6 +23,7 @@ pub fn (a &A2D) set(x int, y int, newval int) {
 		mut e := &int(0)
 		e = a.data + y * a.maxx + x
 		*e = newval
+		_ = e // TODO compiler bug, this is not necessary
 	}
 }
 
@@ -31,6 +32,7 @@ pub fn (a &A2D) get(x int, y int) int {
 	unsafe {
 		mut e := &int(0)
 		e = a.data + y * a.maxx + x
+		_ = e
 		return *e
 	}
 }