next try to add exherbo linux support

I noticed this has changed from your previous PR: https://github.com/opscode/chef/blob/btm/CHEF-5236/lib/chef/provider/package/paludis.rb#L94-L96. If you need to mimic the behavior of `Chef::Mixin::Command#run_with_systems_locale` you can add `:env => ENV` to your `shell_out!` command and shellout will add `ENV['LC_ALL']` by default, if set (https://github.com/opscode/mixlib-shellout/blob/master/lib/mixlib/shellout.rb#L298-L305).