Shutdown mongoose in rl-interface gracefully
When the RL::Interface is destroied but the engine isn't completely shoutdown there was a dangling pointer. The time the dangling pointer is accessable got expanded with rP27908.
Whith this patch there no dangling pointer (in that regard).
Accepted by: @vladislavbelov
Trac Tickets: #5989
Differential Revision: https://code.wildfiregames.com/D5254