* lib/rubygems.rb:  Allow specification of directory permissions.
  [ruby-trunk - Bug #7713]
* test/rubygems/test_gem.rb:  Test for the above.


git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@39607 b2dd03c8-39d4-4d8f-98ff-823fe69b080e