disable crossplay on pc

@g1g2_mozo Bullets from PC users don't like hitting targets who run around corners. Bullets from Console users practically curves to hit. I've noticed getting killed like this a lot more often by controller users. It could be that they're lagging or something, but I can be completely behind a wall, and still get shot by someone on the other side, 5 seconds later. Had an Octane snipe at me, and they missed. The moment I went behind a wall to reposition, they took off my armor and half my health with one shot, and I saw the bullet line go through the wall. This sort of thing was like a "What?" moment.