* vm_trace.c: exterminate Zombies.
  There is a bug that T_ZOMBIE objects are not collected.
  Because there is a pass to miss finalizer postponed job
  with multi-threading. This patch solve this issue.
* vm_trace.c (rb_postponed_job_register_one): set
  RUBY_VM_SET_POSTPONED_JOB_INTERRUPT(th) if another same job
  is registered.
  There is a possibility to remain a postponed job without
  interrupt flag.
* vm_trace.c (rb_postponed_job_register_one): check interrupt
  carefully.
* vm_trace.c (rb_postponed_job_register_one): use additional space
  to avoid buffer full.
* gc.c (gc_finalize_deferred_register): check failure.
* thread.c (rb_threadptr_execute_interrupts): check
  `postponed_job_interrupt' immediately.  There is a possibility
  to miss this flag.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@43383 b2dd03c8-39d4-4d8f-98ff-823fe69b080e