* include/ruby/intern.h: export rb_ivar_foreach.
* include/ruby/ruby.h: modify struct RObject and RClass for optimizing
T_OBJECT space. [ruby-dev:31853]
(ROBJECT_LEN, ROBJECT_PTR)
(RCLASS_IV_TBL, RCLASS_M_TBL, RCLASS_SUPER, RCLASS_IV_INDEX_TBL)
(RMODULE_IV_TBL, RMODULE_M_TBL, RMODULE_SUPER): abstract accessor
defined.
* variable.c: support the modified RObject and RClass.
* object.c: ditto.
* class.c: ditto.
* gc.c: ditto.
* marshal.c: ditto.
* eval_method.ci: use the abstract accessor.
* insns.def: ditto.
* proc.c: ditto.
* struct.c: ditto.
* eval.c: ditto.
* error.c: ditto.
* vm.c: ditto.
* insnhelper.ci: ditto.
* ext/digest/digest.c: ditto.
git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@13543 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
5c0e68c39c