bugfix: should still use timer instead of delayed_events when worker process is exiting,

otherwise the new created 0 delay timer may have no chance to run.

Author: doujiang24

src/ngx_http_lua_timer.c

@@ -329,7 +329,7 @@ ngx_http_lua_ngx_timer_helper(lua_State *L, int every)
     lmcf->pending_timers++;
 
 #ifdef HAVE_POSTED_DELAYED_EVENTS_PATCH
-    if (delay == 0) {
+    if (delay == 0 && !ngx_exiting) {
         dd("posting 0 sec sleep event to head of delayed queue");
         ngx_post_event(ev, &ngx_posted_delayed_events);