Ruby

• method.h: back to share rb_method_definition_t by
  rb_method_entry_t.
  r50728 changed sharing def's to isolating def's
  on alias and so on. However, this change conflicts
  future improvement plan. So I change back to sharing approach.
• method.h: move rb_method_definition_t::flags to
  rb_method_entry_t::attr::flags.
  rb_method_entry_t::attr is union with VALUE because this field
  should have same size of VALUE. rb_method_entry_t is T_IMEMO).
  And also add the following access macros to it's fileds.
  • METHOD_ENTRY_VISI(me)
  • METHOD_ENTRY_BASIC(me)
  • METHOD_ENTRY_SAFE(me)
• vm_method.c (rb_method_definition_addref): added instead of
  rb_method_definition_clone().
  Do not create new definition, but increment alias_count.
• class.c (clone_method): catch up this fix.
• class.c (method_entry_i): ditto.
• proc.c (mnew_internal): ditto.
• proc.c (mnew_missing): ditto.
• vm_eval.c: ditto.
• vm_insnhelper.c: ditto.
• vm_method.c: ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50792 b2dd03c8-39d4-4d8f-98ff-823fe69b080e