Revert "test/rdoc: avoid tempfile leaks"

This reverts commit r46145.

Tempfile.create is only available Ruby 2.1 or higher.
rubygems need to support Ruby 1.9 and 2.0 series.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46683 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
* test/rubygems/test_gem_package.rb: avoid tempfile leaks using Tempfile#close!
* test/rubygems/test_gem_request_set.rb: ditto.
* test/rubygems/test_gem_request_set_gem_dependency_api.rb: ditto.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@46684 b2dd03c8-39d4-4d8f-98ff-823fe69b080e
enumerator.c: Module#enumerable

* enumerator.c (mod_enumerablize): new method to make a method
  enumerable.