Fixing request_app_link reference counting for delayed requests.
Fixing request_app_link reference counting for delayed requests.

Router built with debug may stop with assertion during stalled requests
re-schedule.  This was caused by missing reference counting increment
before nxt_router_port_select() call.

nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit,nginx/unit