Merge pull request #7 from G-Core/fix/sigsegv_on_timer_drop

 don't call ngx_event_del_timer if nginx is exiting

nginx_module/src/timer.rs

@@ -20,7 +20,10 @@ impl<HandlerFn> Drop for Timer<HandlerFn> {
         }
 
         unsafe {
-            if self.event.timer_set() != 0 {
+            if self.event.timer_set() != 0
+                && ngx_quit == 0
+                && ngx_exiting == 0
+                && ngx_terminate == 0 {
                 ngx_event_del_timer(&mut *self.event.as_mut());
             }
         }