record load average at fail

On a high load machine, the following test can fail.
This patch simply records the load average with `uptime`.

```
  1) Failure:
TestThreadQueue#test_thr_kill [/tmp/ruby/src/trunk_gcc10/test/ruby/test_thread_queue.rb:239]:
only 165/250 done in 60 seconds.
```

Author: ko1

test/ruby/test_thread_queue.rb

@@ -235,8 +235,14 @@ def test_thr_kill
           end
         _eom
       rescue Timeout::Error
+        # record load average:
+        uptime = `uptime` rescue nil
+        if uptime && /(load average: [\d.]+),/ =~ uptime
+          la = " (#{$1})"
+        end
+
         count = File.read("#{d}/test_thr_kill_count").to_i
-        flunk "only #{count}/#{total_count} done in #{timeout} seconds."
+        flunk "only #{count}/#{total_count} done in #{timeout} seconds.#{la}"
       end
     }
   end