* vm.c (rb_vm_register_special_exception): make new function to
  make and register special exceptions.
* vm.c (rb_vm_mark): do not need to mark special exceptions
  because they are registerd by rb_gc_register_mark_object().
* eval.c (Init_eval): use rb_vm_register_special_exception().
* gc.c (Init_GC): ditto.
* proc.c (Init_Proc): ditto.
* thread.c (Init_Thread): ditto.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@47534 b2dd03c8-39d4-4d8f-98ff-823fe69b080e