Ignore exception from Process.kill.

On NetBSD this usually raises Errno::ESRCH.
Of course, the process is already finished and should be ignored.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@32034 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

test/testunit/test_parallel.rb

@@ -27,7 +27,10 @@ module TestParallel
             Process.waitpid(@worker_pid)
           end
         rescue IOError, Errno::EPIPE, Timeout::Error
-          Process.kill(:KILL, @worker_pid)
+          begin
+            Process.kill(:KILL, @worker_pid)
+          rescue Errno::ESRCH
+          end
         end
       end
     end