Destroying pool in case of error.

This closes #233 issue on GitHub.
Thanks to 洪志道 (Hong Zhi Dao).

src/nxt_controller.c

@@ -184,6 +184,7 @@ nxt_controller_start(nxt_task_t *task, void *data)
 
     vldt.pool = nxt_mp_create(1024, 128, 256, 32);
     if (nxt_slow_path(vldt.pool == NULL)) {
+        nxt_mp_destroy(mp);
         return NXT_ERROR;
     }
 

src/nxt_runtime.c

@@ -53,14 +53,13 @@ nxt_runtime_create(nxt_task_t *task)
     nxt_app_lang_module_t  *lang;
 
     mp = nxt_mp_create(1024, 128, 256, 32);
-
     if (nxt_slow_path(mp == NULL)) {
         return NXT_ERROR;
     }
 
     rt = nxt_mp_zget(mp, sizeof(nxt_runtime_t));
     if (nxt_slow_path(rt == NULL)) {
-        return NXT_ERROR;
+        goto fail;
     }
 
     task->thread->runtime = rt;