Core controller: fix setting the force_max_concurrent_requests_per_process option
Core controller: fix setting the force_max_concurrent_requests_per_process option

There was a typo. This resulted in Passenger thinking that all processes have
unlimited concurrency.

phusion/passenger,phusion/passenger,phusion/passenger,phusion/passenger,phusion/passenger,phusion/passenger,phusion/passenger,phusion/passenger