Update third_party/protobuf to protobuf-v3.0.0-beta-3

third_party/protobuf/ruby/lib/google/protobuf.rb

 # Protocol Buffers - Google's data interchange format
 # Copyright 2008 Google Inc.  All rights reserved.
 # https://developers.google.com/protocol-buffers/
 #
 # Redistribution and use in source and binary forms, with or without
 # modification, are permitted provided that the following conditions are
 # met:
 #
 #     * Redistributions of source code must retain the above copyright
 # notice, this list of conditions and the following disclaimer.
@@ skipping 26 matching lines @@
   module Protobuf
     class Error < StandardError; end
     class ParseError < Error; end
   end
 end
 
 if RUBY_PLATFORM == "java"
   require 'json'
   require 'google/protobuf_java'
 else
-  require 'google/protobuf_c'
+  begin
+    require "google/#{RUBY_VERSION.sub(/\.\d$/, '')}/protobuf_c"
+  rescue LoadError
+    require 'google/protobuf_c'
+  end
 end
 
 require 'google/protobuf/repeated_field'
 
 module Google
   module Protobuf
 
     def self.encode(msg)
       msg.to_proto
     end
 
     def self.encode_json(msg)
       msg.to_json
     end
 
     def self.decode(klass, proto)
       klass.decode(proto)
     end
 
     def self.decode_json(klass, json)
       klass.decode_json(json)
     end
 
   end
 end