Stopping all application processes if router process dies.

Unit master process restarts the router if the router accidentally dies.
New router process receives the configuration from controller and starts
configured applications.  The information of running applications cannot
be transferred to router because currently there is no persistent application
identifier.  To avoid orphan application processes started by died router,
master process stops all currently running applications once it receives
SIGCHLD for router process.

src/nxt_runtime.c

@@ -435,7 +435,7 @@ nxt_runtime_quit(nxt_task_t *task, nxt_uint_t status)
         }
 
         if (rt->type == NXT_PROCESS_MAIN) {
-            nxt_main_stop_worker_processes(task, rt);
+            nxt_main_stop_all_processes(task, rt);
             done = 0;
         }
     }