Fix disappearing berries due to not miraging.

Reported in https://wildfiregames.com/forum/topic/102351-berries-disappear-in-fog-of-war/, introduced in r16281 / rP16281.
Marks entities as seen by the player, such that a mirage is properly created when some attribute changes.

Differential revision: https://code.wildfiregames.com/D4848
Basically a patch by: @wraitii