enumerator.c: lazyenum_size

* enumerator.c (lazyenum_size): adjust arguments.

* enumerator.c (enumerable_lazy): use lazyenum_size() instead of
  enum_size().

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@41688 b2dd03c8-39d4-4d8f-98ff-823fe69b080e