Fix rpg rocket notifying owner incorrectly

[SamVanheer]

The RPG rocket notifies the RPG that launched it when it has been destroyed.

This doesn't happen if the player launches a rocket and then goes through a level change and the rocket isn't transitioned along with the player, causing the RPG to think there is still a rocket flying around.

This edge case should be fixed to prevent the RPG from becoming unusable when the laser sight is enabled.