[rubygems/rubygems] Make SpecificationPolicy autoload constant

It reduces memory usage about 204kb (1.4%).

https://github.com/rubygems/rubygems/commit/b7d4b8c8a6

lib/rubygems.rb

@@ -1316,6 +1316,7 @@ An Array (#{env.inspect}) was passed in from #{caller[3]}
   autoload :Source,             File.expand_path('rubygems/source', __dir__)
   autoload :SourceList,         File.expand_path('rubygems/source_list', __dir__)
   autoload :SpecFetcher,        File.expand_path('rubygems/spec_fetcher', __dir__)
+  autoload :SpecificationPolicy, File.expand_path('rubygems/specification_policy', __dir__)
   autoload :Util,               File.expand_path('rubygems/util', __dir__)
   autoload :Version,            File.expand_path('rubygems/version', __dir__)
 end

lib/rubygems/specification.rb

@@ -11,7 +11,6 @@ require_relative 'basic_specification'
 require_relative 'stub_specification'
 require_relative 'platform'
 require_relative 'requirement'
-require_relative 'specification_policy'
 require_relative 'util/list'
 
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