* range.c (rb_range_values): use rb_check_funcall instead of
  calling rb_respond_to then rb_funcall, and allow `begin` and
  `end` to be private as well as other internal conversions.
  [ruby-core:83541] [Bug #14048]

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@60416 b2dd03c8-39d4-4d8f-98ff-823fe69b080e