config.load_paths should also be frozen

On Rails::Initializer, configuration.load_once_paths is frozen but
config.load_paths is not.

We need to freeze them so future modifications will fail rather than
do nothing mysteriously. For example, I was changing the variable on
my environment/development.rb and the path I was setting was never
loaded.

To fix, just add the line:

  configuration.load_paths.freeze

To railties/lib/initializer.rb, method set_autoload_paths, around line
214.

So we will have:

  def set_autoload_paths
    Dependencies.load_paths = configuration.load_paths.uniq
    Dependencies.load_once_paths = configuration.load_once_paths.uniq

    extra = Dependencies.load_once_paths - Dependencies.load_paths
    unless extra.empty?
      abort <<-end_error
        load_once_paths must be a subset of the load_paths.
        Extra items in load_once_paths: #{extra * ','}
      end_error
    end

    # Freeze the arrays so future modifications will fail rather than
do nothing mysteriously
    configuration.load_paths.freeze
    configuration.load_once_paths.freeze
  end