Disable outrun in a way that does not generate a warning when rspec/autorun gets loaded.

This is necessary to get the JRuby 9.1.2.0 build passing with the `--dev` flag.

Author: myronmarston

spec/rspec/core_spec.rb

@@ -51,7 +51,7 @@
       # Many files assume this has already been loaded and will have errors if it has not.
       'require "rspec/core"',
       # Prevent rspec/autorun from trying to run RSpec.
-      'RSpec::Core::Runner.disable_autorun!'
+      'def (RSpec::Core::Runner).autorun; end'
     ], :skip_spec_files => %r{/fake_libs/}, :allowed_loaded_feature_regexps => allowed_loaded_features do
     if RUBY_VERSION == '1.8.7'
       before(:example, :description => /(issues no warnings when the spec files are loaded|stdlibs)/) do