Fixing racing condition on listen socket close in router (v2).
Fixing racing condition on listen socket close in router (v2).

This patch fixes a possible race between the nxt_router_conf_wait() and
nxt_router_listen_socket_release() function calls and improves the 7f1b2eaa2d58
commit fix.

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