* include/ruby/ruby.h (struct rb_data_type_struct), gc.c: add
  rb_data_type_struct::flags. Now, this flags is passed
  at T_DATA object creation. You can specify FL_WB_PROTECTED
  on this flag.
* iseq.c: making non-shady iseq objects.
* class.c, compile.c, proc.c, vm.c: add WB for iseq objects.
* vm_core.h, iseq.h: constify fields to detect WB insertion.



git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41412 b2dd03c8-39d4-4d8f-98ff-823fe69b080e