This makes Lazy#cycle no longer needed, so it was removed.
  Make Enumerator#chunk and slice_before return lazy Enumerators.
  [Bug #7715]

* internal.h: Remove ref to rb_enum_cycle_size; no longer needed

* enum.c: Make enum_cycle_size static.

* test/ruby/test_lazy_enumerator.rb: Test for above

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39058 b2dd03c8-39d4-4d8f-98ff-823fe69b080e