Don't hang on SIGHUP in the arena.

Make ui::delay() treat seen_hups in the same way as an ESCAPE key
rather than simply returning. This is only called by the arena code,
and it doesn't check seen_hups itself.

crawl-ref/source/ui.cc

@@ -3394,6 +3394,11 @@ void delay(unsigned int ms)
             pump_events();
     }
 #endif
+    if (crawl_state.seen_hups)
+    {
+        macro_buf_add(CK_ESCAPE, true); // Let the caller respond to seen_hups.
+        pump_events();
+    }
 }
 
 /**