Ruby

merges r21660 from trunk into ruby_1_9_1.

• vm_eval.c, eval.c (rb_f_block_given_p): move definition of
  "iterator?" and "block_given?" to make static.
• vm.c (vm_get_ruby_level_caller_cfp): make it static.
• eval_intern.h, vm_insnhelper.c: move decl. of
  vm_get_ruby_level_caller_cfp()
  from eval_intern.h to vm_insnhelper.c.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/branches/ruby_1_9_1@21850 b2dd03c8-39d4-4d8f-98ff-823fe69b080e