* vm_trace.c (rb_postponed_job_register_one): fix iteration bug.
* ext/-test-/postponed_job/postponed_job.c,
  test/-ext-/postponed_job/test_postponed_job.rb: add a test.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@40967 b2dd03c8-39d4-4d8f-98ff-823fe69b080e