Ruby

• method.h: make rb_method_entry_t a VALUE.
  Motivation and new data structure are described in [Bug #11203].
  This patch also solve the following issues.
  • [Bug #11200] Memory leak of method entries
  • [Bug #11046] callee returns incorrect method name in orphan
    proc
• test/ruby/test_method.rb: add a test for [Bug #11046].
• vm_core.h: remvoe rb_control_frame_t::me. me is located at value
  stack.
• vm_core.h, gc.c, vm_method.c: remove unlinked_method... codes
  because method entries are simple VALUEs.
• method.h: Now, all method entries has own independent method
  definititons. Strictly speaking, this change is not essential,
  but for future changes.
  • rb_method_entry_t::flag is move to rb_method_definition_t::flag.
  • rb_method_definition_t::alias_count is now
    rb_method_definition_t::alias_count_ptr, a pointer to the counter.
• vm_core.h, vm_insnhelper.c (rb_vm_frame_method_entry) added to
  search the current method entry from value stack.
• vm_insnhelper.c (VM_CHECK_MODE): introduced to enable/disable
  assertions.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@50728 b2dd03c8-39d4-4d8f-98ff-823fe69b080e