Revert "third_party/protobuf: Update to HEAD (83d681ee2c)"

third_party/protobuf/src/google/protobuf/source_context.proto

 // 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 18 matching lines @@
 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 
 syntax = "proto3";
 
 package google.protobuf;
 
 option csharp_namespace = "Google.Protobuf.WellKnownTypes";
 option java_package = "com.google.protobuf";
 option java_outer_classname = "SourceContextProto";
 option java_multiple_files = true;
+option java_generate_equals_and_hash = true;
 option objc_class_prefix = "GPB";
-option go_package = "google.golang.org/genproto/protobuf/source_context;source_context";
 
 // `SourceContext` represents information about the source of a
 // protobuf element, like the file in which it is defined.
 message SourceContext {
   // The path-qualified name of the .proto file that contained the associated
-  // protobuf element.  For example: `"google/protobuf/source_context.proto"`.
+  // protobuf element.  For example: `"google/protobuf/source.proto"`.
   string file_name = 1;
 }