Fix monsters attacking across z levels when wandering

[joveeater]

Summary

SUMMARY: Bugfixes "Prevent monsters from wandering into an attack across zlevels when fov_3d is off."

Purpose of change

A monster that wanders or scent moves into the player will ignore fov_3d restrictions when attacking them.

Describe the solution

If fov_3d is off it prevents it from attacking across zlevels.

Testing

Spawned a giant wasp above me. It doesn't attack now.

[chaosvolt]

1. Compiled and load-tested.
2. Spawned in and spawned a wasp above me.
3. Didn't get attacked by an unseen critter.
4. Turned 3D vision on.
5. Can now get attacked, but can actually see my attacker and retaliate.